rear end swap for different gear ratio

[oldcane]

I was only asking about the fit of the T/A rear axle. I seem to remember a thread stating that but can't find it. Maybe it wasn't here. I didn't mean to start an argument about something I know to be true because I see 4.75x5 conversions all over the place.

Really, I don't care because I'm staying 6-lug but thought others might be interested since this thread is about an axle swap.

[Tx Firefighter]

This thread started out looking for an easy swap differential to get a more desirable ratio.

The later model rearends are super common and easy to find. A lot of them had 3.42 in them and a good percentage had the G80 posi option. All of the rearends from 73 and newer will be completely serviceable with parts from anywhere, anytime. The 2nd generation TransAm rearend he motioned is pretty rare because all of the Camaro guys scour around looking for them. But, if he did find one, he'd be left with the car bolt pattern.

Now, on the front, I'm familiar with the 4.75 conversions but they have practical downsides. Speaking of the link he provided for the kit, first consideration is the price at well over 700 dollars. Second is they apparently use the sealed hub/bearing assemblies. That's not a common part. If one fails, and those type of hubs do fail, you're gonna have to order a replacement from them. You can't fix it at the parts store.

It doesn't matter to me personally either way. My choice would be a later model 3.42 rearend from the junkyard and a 5 lug 73-87 front brake swap. I could absolutely buy a rearend, front drop spindles, and 73-87 brake parts to convert the entire truck to five lug for less than the referenced kit cost. And, when parts failed, repair would be simple with locally available parts.

[boostedc10]

Originally Posted by Tx Firefighter

This thread started out looking for an easy swap differential to get a more desirable ratio.

The later model rearends are super common and easy to find. A lot of them had 3.42 in them and a good percentage had the G80 posi option. All of the rearends from 73 and newer will be completely serviceable with parts from anywhere, anytime. The 2nd generation TransAm rearend he motioned is pretty rare because all of the Camaro guys scour around looking for them. But, if he did find one, he'd be left with the car bolt pattern.

Now, on the front, I'm familiar with the 4.75 conversions but they have practical downsides. Speaking of the link he provided for the kit, first consideration is the price at well over 700 dollars. Second is they apparently use the sealed hub/bearing assemblies. That's not a common part. If one fails, and those type of hubs do fail, you're gonna have to order a replacement from them. You can't fix it at the parts store.

It doesn't matter to me personally either way. My choice would be a later model 3.42 rearend from the junkyard and a 5 lug 73-87 front brake swap. I could absolutely buy a rearend, front drop spindles, and 73-87 brake parts to convert the entire truck to five lug for less than the referenced kit cost. And, when parts failed, repair would be simple with locally available parts.

Oh dont get me wrong, I am with you all the way. I just think this thread has gone a few directions.

If the OP wanted to stay 6 lug he is stuck with the truck stuff.

[oldcane]

Good lord. That's just a link I posted for 13" brakes with spindles. Seems cheap to me for the "big brake" kit. There are tons cheaper. I'm sure you can do a lot of things cheaper than I can but I bet there are things I can do with bailing wire that you can't. That's not what I was asking. And I'm not the OP. I was just asking about the TA being a match width-wise. It must not be true because no one has even attemped to answer that in this thread with lots of rear axle knowledge. I thought I was being helpful but apparently I'm just being stupid. I can put a stop to that right now.

[67 cst swb]

On the subject of 5 x 4-3/4 bolt pattern... just to throw a wrench into the subject
71-72 & 73-74 Chevy G10 vans had 5 x 4-3/4 bolt pattern
and they were the same upper and lower ball joints as the respective year pickup and the outer tie rod end as well.
So, if you get 71-72 Chevy Van spindle set up... you use 71-72 Chevy Pickup Ball Joints and outer Tie Rod End
If you get a 73-74 Chevy Van Spindle... you use 73-74 Chevy Pickup stuff

The brake stuff is the same as 70-77 Camaro rotor and caliper

[Fitz]

Originally Posted by oldcane

Good lord. That's just a link I posted for 13" brakes with spindles. Seems cheap to me for the "big brake" kit. There are tons cheaper. I'm sure you can do a lot of things cheaper than I can but I bet there are things I can do with bailing wire that you can't. That's not what I was asking. And I'm not the OP. I was just asking about the TA being a match width-wise. It must not be true because no one has even attemped to answer that in this thread with lots of rear axle knowledge. I thought I was being helpful but apparently I'm just being stupid. I can put a stop to that right now.

GMC Paul has the Chevrolet chassis overhaul manual for your truck that will show you step by step, with pictures, how to rebuild your diff. The manual is $29.95. DTS has the ring and pinion set to fit your case for $191.00 and an additional 100.00 for the complete rebuild kit that has new bearings, seals, shims and the crush sleeve. You get to keep your current axles, wheels brakes and avoid a bunch of headaches while you learn how to set up a diff correctly.
Unless of course you really like the frustration of never being able to get the right parts and you end up throwing your wallet at the problem. Any time you buy a used diff you are paying for somebody else's problems unless you rebuild it and, if you are going to do that, you should be paying for just the case, not a working diff so pay accordingly. Here in Tucson a used 12 bolt truck diff goes for about $150-180.00 and a stripped housing for the same.

[scrapmetalart]

[QUOTE=Tx Firefighter;6673095
an 88-98 truck was very, very, very common with 3.42 gears (like 80 percent of them). Find one with the G80 code on the glove box sticker and you've got a locker too. And it uses the common 5x5 pickup bolt pattern.[/QUOTE]

those the same width as 71 - 72?

[gale]

Originally Posted by Mattys1970C-10

is there any trucks that came stock with a 3.42 and posi? this way I could just swap out the whole rear end and avoid shop labor for a ring and pinion install

Depended on where the truck was delivered as to what was standard. For example GM wouldn't ship a 3.08 to a mountainous region. A buyer could special order up to a point; if it wouldn't meet the EPA requirements GM wouldn't ship. But anyone could order a ring and pinion in whatever ratio they wanted.

[Lees68GMC]

No, those rear-ends have the spring perches (for leaf springs) in the same location but are 2" wider over-all. Actually it works great as it only adds 1" per side moving your tires out board away from the inside plane of the bed's fender wells. Newer trucks have the asymmetric shocks forward & back of the axle plane which you need to change. If your new rear-end you get doesn't have Posi a newer, better design like an Eaton or True-trac can be had for about $425.00

Mines a 78, C-10 12 bolt with 3:42 gears. I run 275-60-15 BFGs (almost 10" tread width) on 5 on 5, 15" X 8" wheels

[Mattys1970C-10]

im tempted to try and rebuild it now....heard its a nightmare and if not done correctly it will whine like crazy and pop eventually. this is all great input, lots of ideas and info on options here.