Rebuild or Replace?

[veinbar]

These are the ratios that I can find for a GM 12 bolt truck rear end. Are there more options than this?

3.08... 40-13 (What I currently have)
3.42... 41-12
3.73... 41-11
4.11... 39-9
4.56... 41-9

[veinbar]

After finding out that my transmission (TH400) needs a rebuild, I have reconsidered my rear end situation. I now want a 3.73 posi or open rear to compliment a 700r4 transmission. I currently have 3.08 gears in my GM 12 bolt rear.

1. Is it possible to find a GM 12 bolt rear with 3.73 gears at a junkyard?
2. If so, which year span of 12 bolt rears would fit my truck?
3. If I rebuild my rear w/ 3.73, where in Austin, TX should I go? (heard of Inland?)
4. Some suggest that I bring the parts, some suggest that I buy the parts through the shop that does the rebuild... Thoughts?

any feedback you may have to offer will be greatly appreciated.

[veinbar]

I have decided to have my 12 bolt truck w/ 3.08 gears rebuilt with 3.73 ratio and posi unit. Can anyone tell me what I will be purchasing in this process? What parts can be reused?

[veinbar]

Here's a quoted text from the mechanic who is going to rebuild my 12 bolt...

"gears are toast... pinion bearing got loose causing bearing to fall towards ring gear and then they just get tore up from there... i have a parts list if u can come by sometime and we can talk about it..."

Doesn't sound good at all. Any guesses out there on repair costs?

[Jonboy]

Maybe it will be just gears and a setup kit with bearings. You can always hope.

[78 Chevyrado]

This may not help much, But I'm currently rebuilding my dads ford 8.8 in his F-150. an axle went bad and all the metal from that flowed through everything else resulting in badly pitted gears and bearings... the carrier bearings were shot too. So he needs everything except the case itself, I just bought all the parts, nothing high performance other than the LSD carrier and 31 spline shafts and it's costing about $1100. and that's with no labor costs.

[veinbar]

Originally Posted by 78 Chevyrado

This may not help much, But I'm currently rebuilding my dads ford 8.8 in his F-150. an axle went bad and all the metal from that flowed through everything else resulting in badly pitted gears and bearings... the carrier bearings were shot too. So he needs everything except the case itself, I just bought all the parts, nothing high performance other than the LSD carrier and 31 spline shafts and it's costing about $1100. and that's with no labor costs.

That would be a nightmare. I still don't have a quote yet, but possibly stopping by after work. I'll let you guys know what the estimate is. I'm getting a little bit of a deal because I'm tuning up a couple of bikes for him. Somewhat of a trade off.

[LONGHAIR]

From my earlier post....

Originally Posted by LONGHAIR

Personally, I would recommend looking for a used rearend. It may take a little work on your part, but it will come out a lot cheaper. Inspecting the axle is not that hard, but you do need to do it to be sure of what you are getting.
You want to be sure to pull the cover off and see inside. This will assure you of the gear ratio in the first place, but more importantly you can see the actual contact area of the gears.

While doing this you may come across an axle with a "Gov-Lock". It's a factory positraction unit. In a light duty application, they are OK, so it's not necessarily a "deal breaker".....but don't pay any extra for it.

Even if the used axle does fail on you after a few years, it was cheap in comparison. Sure there is some work involved, but you can save quite a bit of money for your efforts.

As always, synthetic lube is your friend here. Cheap insurance.