MD 3.73:1 14-bolt

[special-K]

I'm offering this complete drum to drum full-floating rear to 67-72 C/20 and C/30 single wheel owners as an economical way to get a better hiway gear,that still will haul,as well as a 32 or more year younger rear axle that parts are readily available for. I'm selling it for what a ring & pinion set would cost,if you could find one. I removed this rear from my '95 K3500 single rear pickup when it was 4 years old. I swapped in a 4.10 when I went with larger tires to match what I felt worked well in my '92 with same tires/motor/trans. It has between 55-60k on it and has been stored since '99. Maybe someone close enough could use this. The spring and shock mounts will need relocating,which is a simple matter..........$200...USPS money order

[duallyjams]

pics=drum to drum measurement=bump

[special-K]

I'll traipse out through the deep snow and get some pics and a measurement

[special-K]

ttt...It looks like a full-floating rear and you can't see the 3.73 gears It's not rusty and scaly. It's good enough to paint all purdy. The 88-98 14-bolts are the same width as 60-87,just have different spring and shock locations. But,all 14-bolts require this work,which is way easier to do (or cheaper to have done) than change a ring & pinion

[special-K]

I still have this wonderfully hiway friendly rear axle

[special-K]

This rear is $200. If you could even buy 3.73 ring & pinion sets for the HO52 they would cost more than that,then pay labor and other parts involved. And,you get readily available brake part to boot! Cruise that 67-72 8-lugger down the hiway a notch better with an updated rear for less than the cost of a pair of tires.

[special-K]

New price...$400


Just Kidding!!!!! (I don't seem to ever sell parts for what they're worth)

Someone just sold the lighter duty 9.5" (this one's 10.5") semi-floater ring and pinion for $170 shipped on another parts board here. That's just a used ring & pinion for the light duty 14-bolt semi-floater that needs to be installed,not the entire unbeatable 14-bolt full floater axle assembly complete with brakes.*

* Not knocking the other guy's price. Just using for an example of what a deal mine is.

[duallyjams]

wonder if you moved this to the 73 & up parts board if it would do better seems to be more 4x4 people.

[special-K]

Maybe,and I appreciate the tip. But,3.73s were available in those years and most guys with 67-72 C/20s want more hiway friendly gears and parts that are easier to find.

[special-K]

Here's he deal. I hear people saying it's not worth changing from 4.10 to 3.73,there won't be a significant difference. That's just not true. Ok,define significant. A significant difference would be going from 10 mpg and a reasonable hiway speed of 60 to 20 mpg and 80 mph hiway speed. What rear's going to do that? Will your truck have any guts? Short of going to an overdrive transmission,which is a significant amount more work and significantly more expensive,going to 3.73s is a very noticeable difference in cruising speed,yet will retain plenty of grunt...AND,if later on down the road you decide to go with O/D,it's a good ratio for that. Why do you think I changed from this 3.73 to 4.10s if it's not much different? My '95 was a heavy truck...diesel w/utility body full of tools (in bins as well as the bed),with heavy duty ladder racks that were usually hauling ladders and scaffold,and usually hauling a trailer full of materials. The truck was turbo charged and a 5spd. I went ti taller tired and it lost it's grunt due to turbo lag. I used granny real quick much of the time,or worked the clutch. I had the same truck in a '92 with 4.10s and it performed just right,so I changed ratios because "it does make a big difference".

If anyone is interested,I would be gad to set this up for a 67-72 for additional money for a bolt-in deal. I know having to make it work has been a hang-up to some that showed interest. The cost is only $200 as is or for another $100-150 I'll move the spring pads and shock mounts to the 67-72 locations,according to what the buyer has.

[va72longhorn]

Tim, you know what I'm working in the longhorn, 402 pushing a 4:56 through a turbo 400. I've wanted to find a way to drop the rpms. If I do ever pull anything, it may be an occasional loaded horse trailer that's less than 5000 lbs. Is the a direction I might wanna go?
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[John Pasinski]

I have a '72 C30 SRW w/ a 4:10.
Ive been searching high & low for a rear w/ 3:73.
Ok......Here's my question would you take a guess as to how much to truck this to Orlando?
I'm not sure how I'd go about it, or even if you're interested in working this out. Whaddya think?

[special-K]

Originally Posted by va72longhorn

Tim, you know what I'm working in the longhorn, 402 pushing a 4:56 through a turbo 400. I've wanted to find a way to drop the rpms. If I do ever pull anything, it may be an occasional loaded horse trailer that's less than 5000 lbs. Is the a direction I might wanna go?
Posted via Mobile Device

3.73s pull just fine,especially behind an automatic. 402s normally came with 3.54s in C/20s,but I guess the C/30s wouldn't have the Dana60. I'm still surprised your truck wouldn't have 4.10s being an automatic. My friend has a '85 that started life as a K/10 and now has '87 k/30 axles and suspension. They are 3.73 and his tires are 285/75-16s,which are about 32". He hauls cars and light trucks on an equipment trailer on a regular basis...weighing far more than 5,000# and he still has the 305 in it.

Originally Posted by John Pasinski

I have a '72 C30 SRW w/ a 4:10.
Ive been searching high & low for a rear w/ 3:73.
Ok......Here's my question would you take a guess as to how much to truck this to Orlando?
I'm not sure how I'd go about it, or even if you're interested in working this out. Whaddya think?

John,let's see what va72longhorn says. I'd work with you on shipping. I think it would have to be on a pallet and shipped freight.

[va72longhorn]

Is there a option # on the spid or somewhere else that would tell me which rear is in it? If nothing else, i can climb under it and see if I can find a tag tomorrow. I know I'm running about 3600 rpms @ 60 mph and someone had told me before that they thought it had the 4:56 option in it. I think either way, we can work something out since we're close in distance, if you think it'll make a big difference and to can get it to bolt right in.
Posted via Mobile Device

[jocko]

If there is no rear gear reference on the SPID, then I believe that would mean your truck left the factory with a 4.10. But that still doesn't mean it may not have been changed out somewhere along the way. Best to drop the rear cover, count teeth on ring & pinion.

[John Pasinski]

OK......I'll wait and see what va72 longhorn chooses.
I appreciate it Special-K.

[va72longhorn]

I'll tell ya what, Tim. Go ahead and see if you and John can work something out. If it falls through, come back to me. I have time before Im anywhere near ready for this move, as Im sure John is alot closer to needing it. Im going to verify whats in mine and then we can go from there. If John ends up with it, youve at least have me headed in the right direction as I didnt realize that it was such an easy swap.

[John Pasinski]

That's very generous of you sir, thankyou.
Special-K..........do you think you'd be able to put something together? I've never done anything like this before and I wouldn't know where to start.

[special-K]

Ok,as far as what's in the C/30 Longhorn I'm willing to bet it's a 4.10'inless someone changed it...and I can't imagine why anyone would with an automatic. 4.57s would certainly be an option if original and listed on the SPID. But,I don't believe GM even offered that as an option.

Ok John, what's involved is I'll have to come up with a pallet or make one and strap the rear to it.Then,get a quote from a common freight carrier. The reason being,it must be moveable by forklift. I'll get on it but it might take a while. I'll keep you informed.

[jocko]

Special-K, reference question for me, in the stock 72 C20 rear end that came with 4.10s, is it possible to change in just a 3.73 ring and pinion onto the existing carrier or must the carrier be swapped out completely - OR - is it even possible in the C20 rearend without using a whole later rear like you are selling.

Just asking for my own information JUST in case I do this swap in the future. If I was doing it right now, I'd be in line for this good deal - I do realize what you're selling is less expensive than any ring and pinion swap - just asking for my own info. Thanks.

[special-K]

Originally Posted by jocko

Special-K, reference question for me, in the stock 72 C20 rear end that came with 4.10s, is it possible to change in just a 3.73 ring and pinion onto the existing carrier or must the carrier be swapped out completely - OR - is it even possible in the C20 rearend without using a whole later rear like you are selling.

Just asking for my own information JUST in case I do this swap in the future. If I was doing it right now, I'd be in line for this good deal - I do realize what you're selling is less expensive than any ring and pinion swap - just asking for my own info. Thanks.

For the 3/4t HO52/1t HO72 rears,4.10 is the tallest gear GM offered. Back when these were current trucks,the aftermarket made 3.90 gear sets and,yes,they would work. These rears are all just one size carrier,unlike 12-bolts and other light duty rears.

For Dana60 rears,which were in some 3/4t and even a few GMC 1/2t trucks,the same is true that they were all the same size carrier. GM offered 3.54s in big block/TH400 trucks. They never offered 3.73s,but Ford did and probably Dodge and IH,but I can't say for certain.

[jocko]

thanks Special-K, good gouge. I think if I had the Dana60, I'd look for a 3.54 gear if it had deep ones in it - even if I had a 350 so highway use would be a little more bearable. I wonder if any aftermarket companies still make 3.XX gears for the Eaton? (the Eatons are the HO52/72, right?) Wow, hard to imagine 4.10 was the tallest! I have seen the 4.56 (I think) optioned ones on SPIDS.

So, just so I'm sure I got this right:
- Dana came with 4.10 set standard, unless behind a big block, which would have gotten a 3.54 r&p as standard (or was 3.54 in a Dana just an option?).
- Eaton came with 4.10 for big and small block (no lower numerical gearset available than 4.10 in Eatons).

Is that right?

And other make (ford/dodge, etc) carriers are a drop in for the Dana? Sorry so many quesitons, I feel like a hijacker!

Maybe I should just buy your rear end and hang onto it!!

[John Pasinski]

"Ok John, what's involved is I'll have to come up with a pallet or make one and strap the rear to it.Then,get a quote from a common freight carrier. The reason being,it must be moveable by forklift. I'll get on it but it might take a while. I'll keep you informed."

That's fine; take your time. I'm hoping the freight & insurance are going to be affordable. I'm sending the cab out for blast, repair, & paint, so the truck's down right now. Anyway, I can install anytime. Besides, us old guys tend to require extra time on stuff like this. Lift with your legs!

[special-K]

Originally Posted by John Pasinski

"Ok John, what's involved is I'll have to come up with a pallet or make one and strap the rear to it.Then,get a quote from a common freight carrier. The reason being,it must be moveable by forklift. I'll get on it but it might take a while. I'll keep you informed."

That's fine; take your time. I'm hoping the freight & insurance are going to be affordable. I'm sending the cab out for blast, repair, & paint, so the truck's down right now. Anyway, I can install anytime. Besides, us old guys tend to require extra time on stuff like this. Lift with your legs!

You mean,lift using young man? It's got wheels mounted for ease of handling and I'll probably roll it to the engine hoist,then set it on the pallet in the bed of my truck. Just to be clear,are you interested in it as is or did you want it modified to bolt in? Either way I will get the shipping quote first.

Originally Posted by jocko

thanks Special-K, good gouge. I think if I had the Dana60, I'd look for a 3.54 gear if it had deep ones in it - even if I had a 350 so highway use would be a little more bearable. I wonder if any aftermarket companies still make 3.XX gears for the Eaton? (the Eatons are the HO52/72, right?) Wow, hard to imagine 4.10 was the tallest! I have seen the 4.56 (I think) optioned ones on SPIDS.

So, just so I'm sure I got this right:
- Dana came with 4.10 set standard, unless behind a big block, which would have gotten a 3.54 r&p as standard (or was 3.54 in a Dana just an option?).
- Eaton came with 4.10 for big and small block (no lower numerical gearset available than 4.10 in Eatons).

Is that right?

And other make (ford/dodge, etc) carriers are a drop in for the Dana? Sorry so many quesitons, I feel like a hijacker!

Maybe I should just buy your rear end and hang onto it!!

I think 4.57s were the standard 4spd ratio and 4.10 was automatics for the HO52 Corporate rear. 3.54 Dana 60s were only in big block automatics. In a BBC/TH400 truck you could "only" get the Dana 60 in 3.54 and that's the "only" way you could get 3.54s. A big block 4spd would come through with 4.10,I believe. Now,on a C/30 you could only get a Corporate rear since the Dana 60 is a 3/4t rear.
Some people call the Corporate rears Eatons. Eaton made the center section,just like in 10 and 12-bolts,but they are GM rears,hence the name "Corporate". Dana ratios run .01 off from the Corporates. Dana made 4.11s and 4.56s,kinda funny,but you look in the parts book and you'll see all four ratios.
A Dana 60 differential is a Dana 60 differential no matter what truck they came in. Each company may have varied axles/spline count/housings/hubs/brakes,etc,but they started with a stock Dana 60 assembly from Dana/Spicer. Later on in GM trucks,when the K/30s came out,they offered 3.73s. So,the front axle being a Dana 60 would have the gear set needed for the Dana 60 rears that came in these trucks. But,you can just buy that gear set over the counter today. Just saying,many 4-wheeler guys using the Dana 60 front axles want to remove the taller gears. I'm guessing you could still buy 3.54s from Dana.

[John Pasinski]

[QUOTE=special-K;5468183]You mean,lift using young man? It's got wheels mounted for ease of handling and I'll probably roll it to the engine hoist,then set it on the pallet in the bed of my truck. Just to be clear,are you interested in it as or did you want it modified to bolt in? Either way I will get the shipping quote first.



Hmmmmmm... Since I've never done this before, how much extra to modify for me? It's very generous of you to offer this. I like the plug and play idea.
I'm sure the angle of the mounts is just as critical as the mount placements. I'll be fumbling, bumbling, & stumbling. I'll bet this ain't your first time doing this.
It's going in to a '72 C30 w/ leafs.