I was wondering if someone could provide a simple photo of a pinion gear for a 12 bolt Chevy truck (2wd 1/2 ton) I'm right in the middle of having someone do the rearend gear swap for me, and am finding out that the crush sleeve and (what I would call) the "inner" pinion bearing that came in my rebuild kit are not wanting to work with the pinion gear. (Ring and pinion numbers both match) The inner pinion bearing will not slide down far enough, and the crush sleeve appears to be too long. Carrier bearings worked ok.

This is going in a 1979 Chevy Heavy Half (or Big 10) 1/2 ton 2wd pickup, with a 12 bolt rearend. Here is the casting number off of the ping and pinion gears that were "given" to me. (In a circular pattern)... 3988516 11:41 GM 3 11 7 8 (hard to tell if it's 7 8 or 78)

At least I know I have the proper series 4 carrier, and that the ring gear "is" 8.875 inches. (or 8 7/8) If anyone is able to help at all I would appreciate it. It sounds like possibly my ring and pinion are from a different "age" application, which might explain why the inner pinion bearing won't go all the way on...??

Thanks for your time, and any help.

Measure the pinion gear shaft just below the teeth, where the bearing sits. If it measures ~1.625", it's for a 12 bolt car. The trucks measure ~1.4375". As far as I know, all 12 bolt truck rearends are identical. The ring gears have the same bolt patterns, so they would interchange. Hope that helps.

Try this link: http://www.2quicknovas.com/happyrearends.html

Thanks guys for the info! I'll let you know something this evening.

Well I contacted my mechanic today, he said he found an inner pinion bearing that will work, and I'm assuming the proper crush sleeve. He stated the ring and pinion that were given to me would work, but something about the housing around the carrier would have to be ground or cut out, to allow the carrier to fit...? Sorry, I know I'm being vague about all of this, but just reporting what he told me. It may be Monday night before I get to pick up the truck, but when I talk to him in person I'll try to get more details on exactly what all he had to do in detail.

What did I learn from all of this? Either buy a "new" complete assembly, (carrier, ring and pinion, etc) or pull everything from the "same" axle, from a known vehicle. (sigh)

Well... since we last met, I've tried to make an appointment out of town with a mechanic who stated he would do the labor for $100, only to find out "the shop was closed due to a family emergency, etc, blah blah blahhh" (same guy who gave me the ring and pinion) So after scheduling with a local mechanic, today I found out that that the ring and pinion that was given to me, was WRONG. After contacting most of the local salvage yards, I found out they don't have the gear ratio I want, or want to sell me a complete rearend... but aren't sure if they even have one with the ratio I want. So I finally said "FORK IT", and ordered a "new" ring and pinion for about $180. <sigh> It should be in around Thursday. (are we there yet????)

HI! I have the same rearend in my '78 Chvey half ton 2wd. Do you know what the spline count is on them? 28? or 30? Thanks, and good luck with yours!

30 spline.

Hey don't forget to buy a rebuild kit with all new bearings, if you don't you are asking for trouble. Well worth the money in the long run, and get a good-complete kit !

Yeah, I got a series 4 carrier, and a complete rebuild kit. Just that the ring and pinion was for a different application.