47-55.1 52 gmc 6 lug rear axle options

[tantrumpipeline]

I've tried the search bar and can't seem to find a straight answer. What is the best option for a 6 lug rear axle when swapping in a 350/350 combo? I have a k10 rear axle for nearly free but there's conflict on whether it's too wide or not as goes for running a camaro style 10 bolt and being able to swap in 6on5.5 axles. Any help is appreciated I'm not even in teardown on the 52 yet just collecting junkyard and used parts to gauge my needs.

[dsraven]

are you looking for an axle that is the correct width srom the get-go or are you open to shortening one side? I ask because the ford 8.8 that comes in an explorer is a pretty stout unit, is available with posi and big axles, disc brakes etc. and the centre section is offset to one side a little. what some fellas have done is to shorten the long side so they can use two short side axles. yes, the bolt pattern is 5 stud but that can be re-drilled or possibly you will be doing some front suspension work and will be swapping to a 5 stud front wheel so the ford axle flanges could be drilled to match the front. I have done the redrill thing to fit a chevy pattern, like the S10 uses, and it was easy. I used an old disc brake rotor from an explorer, marked and drilled 1/8" holes between the ford pattern holes, then mounted it up to the ford axle, using the ford wheel studs to keep things lined up well, then drilled through the 1/8" holes to mark the axle flange. removed the template and did the same for the other axle, then simply drilled those spots for the correct size wheel stud. the rest is self explanatory and you will need to drill the new brake rotors as well.
the 8.8 has a write up on "the ranger station" as far as what came from where and updates, mods etc. there is also lots of aftermarket support for high performance stuff, like c clip eliminators etc. they are about the same in comparison to the chevy 12 bolt but less money and easier to find. narrowing is relatively straight forward ad lots of guys have done this in their home garage.
otherwise I would look at the S10 axles, there are a few widths available with the ZR2 sport truck being the widest. lots of guys put an S10 frame under their AD trucks so the S10 is likely pretty close to the right width but, again, only a 5 stud axle.
personally I would try to find something from a newer vehicle rather than use something from the same era as your truck came with. if you are upgrading the rear axle to be an open suspension then remember the original torque tube rear suspension mounted the axle on a hinge, basically, so there is a axle centreline issue if you simply bolt a different, open style, axle up to the same spring centre bolt. thats a whole different conversation but easy enough to get around.
if thinking of an S10 axle joedoh would be the go-to for info on what width works the best because he does the S10 frame swaps a lot and sells the frame brackets to mount the old body on the newer frame.
post up some pics of your truck and what you plan to make it look like when you're done. will it be a daily driver, trailer quen, stock except for the rear axle?

[dsraven]

if you google
the fabrication series how to narrow an 8.8
there is a couple of youtubes that show how this fella does it

here is a link to the ranger station's wriote up on the 8.8
https://www.therangerstation.com/tec...ory-and-specs/

track width

https://www.crankshaftcoalition.com/...l_measurements

hopefully those help

[leegreen]

63-70 2wd pickup is 6 bolt and the right width. If it comes from a trailing arm truck you will need to weld on spring pads.

4x4 S10 or chevelle / camaro rears are known to fit as well but are not 6 bolt

[whitedog76]

I've actually been thinking about using a Chevy Trailblazer rear on my truck. The WMS is right around 63" which is good. They also have healthy rear disc brakes, also good. They can be had for Cheap at most all wrecking yards, which is great.

The bad is that there is lots of brackets, etc.. that need removed from the 4 link, coil pads, etc... The really bad is they have an odd ball bolt pattern that would require the axle shafts to be redrilled to 6x5.5.

[tantrumpipeline]

Awesome info thanks guys. I’m just going to update the truck from a safety standpoint and make it a little more cruise friendly as I’m in northern Canada and it’s fun to drive to shows rather than tow toys. I’m just collecting parts right now as my 68 is a few weeks maybe two months of tinkering from being on the road again finally and my 77 should be off to paint by may then the 52 is into the garage. Plans for the 52 are Altman latches, CPP disc conversion and taper bearing upgrade (allowing for 5 bolt but I have 6 bolt transits with dog dishes from another build leftover i was hoping to use), swap in a 350/350 setup and a newer rear diff, add frame bracing, rebuild the front end, undecided on mounting rack and pinion to the straight axle or doing a CPP power conversion, adding seatbelts, under bed fuel tank, holley sniper efi, then a little bodywork and give it a splash of matte army green

[mr48chev]

Originally Posted by leegreen

63-70 2wd pickup is 6 bolt and the right width. If it comes from a trailing arm truck you will need to weld on spring pads.

4x4 S10 or chevelle / camaro rears are known to fit as well but are not 6 bolt

63/68 or nine as I think 70 is a little wider GMC trucks had leaf springs rather than coil springs on the rear.

I'm thinking that the 3.70 rear end that was under the 70 I had that I sold to a friend for his 65 was a bit wider than the 65 rear end that is under a trailer I have was. The only issue there was the deep reverse wheels he had on it were a tight fit in the stepside fenders. stock rims wouldn't have been an issue.

[tantrumpipeline]

You bet the 70 is wider I had a 70 rear in my 68 and had to replace it to fit my 5 lug swap but that should work better in the AD

[dsraven]

from a wreck I had, an 04 envoy awd, the rear axle, from wheel mounting axle flange to axle flange, with no brake rotor installed, is 65 5/8 inches across. I gotta think with the rotors installed it would be 66 inches from side to side. I have one under my 57 but iy has the stock envoy wheels on it for now not much of a dish to them, like a front wheel drive vehicle really) and I can tell you there isn't much romm between the sidewall and the fender. i also don't have a stock box on it though. you couild do your own math with the measurements i gave.

[whitedog76]

Originally Posted by dsraven

from a wreck I had, an 04 envoy awd, the rear axle, from wheel mounting axle flange to axle flange, with no brake rotor installed, is 65 5/8 inches across. I gotta think with the rotors installed it would be 66 inches from side to side. I have one under my 57 but iy has the stock envoy wheels on it for now not much of a dish to them, like a front wheel drive vehicle really) and I can tell you there isn't much romm between the sidewall and the fender. i also don't have a stock box on it though. you couild do your own math with the measurements i gave.

That's good to know. I always thought they were 63-64". I wonder if there is any difference in the 8" vs. The 8.6" models.

[dsraven]

I think you will find the trailblazer.envoy rear is a little wide from wheel mounting surface to the other side. I would advise a run to the wrecker or check a kijiji ad for a parts truck and measure that.
easy to redrill the axles for the pattern you need as long as the hole in the middle will work. check the wheelsize.com site for offset etc.

[tantrumpipeline]

Ah gotcha that makes sense thanks for the info and photos I better do a little measuring with the factory box and offset of these wheels it may be easier to just accept the 5 bolt wheel and find a wheel that has that same look

[mr48chev]

Chevy Colorados have 6 on 5-1./2 but you have to really know what you are looking at as they have three different widths that I know of.

There is some pretty good info here. https://talk.classicparts.com/thread...-1-3-16.22271/

The good with that thread is that they also tell you how to figure out the gear ratio by looking at the spid so you don't have to get under it or take anything apart to check ratios. The bad is that in some areas the prices seem to be pretty high.

[dsraven]

if scooping a diff from the wrecker or from a vehicle with the vin still available one can always call a dealer parts dept and ask them to check the axle ratio.
not sure if the v8 envoy/trailblazer has a wider axle as the 2 I have wrecked were the 4.2l inline 6 engines.

[tantrumpipeline]

Right on thanks guys I’ll do some digging I have a few months to figure this all out but the info y’all put up should be huge in helping me get this right

[dsraven]

doesn't sound like you are new to the game or that you are afraid to tackle something for a first time, so, personally, I would grab an 8.8 diff from an explorer and shorten the long side to match the short side, then use 2 short side axles. some will say they get a "set" from torquing one direction so you shouldn't put it in the wrong side. well, the easy fix is to buy a new axle if it worries you.
for steering, if you plan to use the stock axle, i would recommend the ccp power steering kit and when you remove the old gearbox you can cut the column and shaft off at the box and then shorten it as much as needed, then use a flanged bearing that fits the dimensions of the old tube and the old shaft (I hear some wheelbarrow wheel bearings fit) then grind some flats onto the shaft to accept a regular column shaft u joint. that way you retain the rest of the column so the interior looks the same and no messing around with a new column etc.
for brakes I would use a hydroboost pwer brake unit from a donor vehicle and attach a master cylinder that fits your brake set up, whether that be disc disc or disc drum. it can be frame mounted like the old stock one. there are guys on here who have done that and simply made a bracket to mount the set up further back to allow more room where the trans is. you can use the front disc brake set up from a supplier or fab something to adapt brakes from something else like some here have done.
it all comes down to how much you have to spend, how much you are willing/able to do yourself and what tools and shop space you have to do it in. oh yeah, and what skill level you have for this kinda thing, haha.
nive pics. keep posting up as you go along.

[tantrumpipeline]

You bet it’s not a major time crunch at this point I have my other trucks near ready to go so I can actually tinker a bit with this one. The 8.8 are all over the place up here too. Big fan of CPP stuff I have it in both my c10’s definitely going to do a fair bit from them and I think I’m going to sell my transits to a buddy and get the 5x4.75 flat smoothie from us wheel and put the 52 dogs on it then do the firewall mounted booster with a disc/disc setup and have no worries just have to somewhat be careful it’s a slippery slope my 68 was supposed to be a quick splash of paint and disc conversion and 13 years later it’s a nut and bolt restoration with way too much time and money invested haha

[dsraven]

if doing a firewall mounted brake system you may wanna look at the newer trucks with the removeable sheet metal section that unbolts from the firewall and includes the booster, master cylinder, pedal assy and may also have the drive by wire accell pedal included. the system i am using is from the envoy, so I used the floor and firewall from the envoy donor because my 57 floor was rotted up to the ankle level. that swction included the stamped steel bubble with all the above parts included. if you plan to install a drivelone that will need a bump out (or in) for the trans tunnel then maybe looking for a donor with the appropriate parts (engine, trans, rear axle, firewall/floor/brake and pedal combo etc) would save you some cash. personally, I bought an insurance write off envoy, stripped it of what I would potentially need, and sold the other parts for more than I paid for the wreck. later, I bought another envoy and stripped off some more parts and sold the parts for a profit. I sold stuff cheap to move it and give the next guy a break. still made a profit, however modest.
long story short, there is a benefit from just buying a kit or a new aftermarket part for what you need. it makes the project move along quickly if you happen to have the disposeable income to do that. myself, I like to strip stuff, make parts from something else fit what I am building and sell off what I don't need just to make the ends meet. the next guy gets a deal and I break even.
just for reference this is what I am talking about for the newer truck sheet metal bubble which includes the booster, master, accel pedal, a grommeted hole for the steering column shaft anothe rhole for wiring to pass through.

[tantrumpipeline]

I never seen that setup before I guess I didn’t really look at ours I just sold an envoy haha that sounds like a good way to do it

[dsraven]

one of the benefits is that the bubble thing sets the whole thing outward into the engine bay a little so you gain a little room inside. downfall is it sets the whole thing outward into the engine bay a little. haha
other gm trucks also use this idea too, I think, so a trip to a wrecker or simply eyeball under the hood of a few friend's trucks to see if a different model has something better suited. something with a hydroboost would be nice, possibly, as they take a little less space. you gotta do a little plumbing from the p/s pump though.

[jweb]

If you plan to use an Explorer you won't need to shorten one side.

I have one under my 51 with 1" spacers. The stock Explorer 8.8 is 59 1/2" wide.

Also, the transit wheels have 5-6" backspacing ( I can't remember the exact). So you could use the 8.8 with adapters to make it all work.

Some people are afraid to use adapters but they're a good way to dial in the exact width you need. Just spend the money and buy good quality ones that are hub centric on the rotor and the wheel. I have a few thousand miles on mine with no issues and plan to do the same on my 64 Suburban with an 8.8 and transit wheels

[tantrumpipeline]

Ah ok that makes sense too but even with a sbc they have a fair bit of room in the bay so not a bad deal. That’s sweet for the transits too and I’m not worried at all I had a set of aluminum adapters on my diesel to run a set of used wheels on it and never had an issue with a 1 ton that is an oil patch truck and tows a 15k lb toy hauler regularly I just check the torque regularly. Think I’m gonna do that firewall mount and snag an explorer with adapters ���� been finding a few decent deals even on Facebook marketplace up here

[mr48chev]

Starting to be too much nonsense and "what I likes" on this.

First if you know what wheels you want to run or actually have them you need to know the back spacing and then add in the amount of space that the tire takes up beyond that.



Stock AD bed with comes out to right at 50-1/8 give or take with the inside width being 50. You have a 74-1/2 outside the fenders to outside the fenders. Take off about 1/2 inch on each side for fender lip and it may be more than that and you have 73-1/2 and still need tire to lip space. You have right at 11-3/4 on each side to work with withoug messing up the fenders or tubs

If your wheel has a 6 inch back spacing that means you need 66 inches of axle width wms to wms just for the rims to clear, Add another inch for tire and that comes to 64 so a 65 inch wide 70 somethign axle is probably what you actually need rather than a 59-1/2 inch exploder rear or worse yet an exploder rear that is narrowed more yet for what ever reason.

There is space for a 255 tire on an 8 inch wheel in side the fender no matter what axle or what offset you run. It is just axle width and offset have to match. it doesn't matter if the 255 is on a 15 inch wheel or a 20 inch wheel it is going to be the same width.

I've played with this tire size comparison chart quite a bit as it puts the numbers side by side

This is comparing a 255-60-15 to a 255-45- 20



This one compares a 255-60-15 to a 255-35-20 you end up with a 20 inch rim but tire height and width is almost exactly the same.


Link to tire calculator https://www.tacomaworld.com/tirecalc

I've used this one at times too and it gives a visual https://tiresize.com/comparison/

Meaning that first you check the back spacing on the wheels and then you may be able to run that K 10 rear, The offset on the wheels and the back spacing will just look funny to most of us AD and TF guys who's preference runs to a more traditional negative offset (reverse) wheel.

I'm thinking that there right at 12 inches of usable width between the fender lip and the bed side of an AD truck, That gives you an inch on each side of the tire wiggle room and I think I actually have 1/2 inch on the inside and maybe 3/4 on the outside.

[tantrumpipeline]

Oh man that calculators a game changer why have I never seen this before? Thanks for the post this actually works out the transports will not need a spacer on the k10 axle to fit so I can do it even cheaper. Thanks for the info had I seen this before building my 68 I would have left the 70 rear axle in it cause now I’m doing a 1” spacer to bring the wheel away from the box sides for clearance

[mr48chev]

The axle will work with those wheels and wheels with the same back spacing

If your wheels are the 22 x 9 it is going to be snug but doable. With wheels with the negagitive offset that mine have the tires would be four or five inches outside the fender like a redneck 4x4.