So there's a guy selling a 10 bolt posi with 3.73 gearing and disk brakes for $300.

What would be some questions to ask or things to look for before knowing if it may be worth purchasing for my '83 TA.

I have drum brakes and either an open diff or worn posi unit now with 3.08 gears. Since I wanted to change the gears and the posi I'm thinking this could be a easy way to change all that and only have to do the work of changing some brake lines and hardware.

What do you guys think? And type slowly - I'm a noob to all this.

 

What type of discs, Delco-Moraine (iron) or PBR's (alum)? If you have the old-style iron combination valve, it'll have SAE threads, so you'll need a disc valve from that era, since later valves are metric. Swapping in a new valve might be a pain.

Drop the diff cover and take a peek for broken teeth and/or excessive wear. Check the pinion seal as well as the axle seals for weeping (which could mean grooved axles).

You might PM big gear head if he doesn't pop in.

JamesC

 

You are probably just taking a chance on that rear end. If it has an Auburn in it then there is no way of knowing how close it is to being worn out. You don't know how the gears were set up, so putting it in the car and giving it a test drive is the only way you are going to know if it's good or not. You can check for metal in the bottom of the housing, but with an Auburn that won't tell you a lot about it either.

 

ok.

That's kind of what I thought. Just trying to find the most economical and effective way of updating the rear end. Everything in mine works fine right now except the posi (it's either worn or an open diff). I really don't mind the drum brakes for now so if it does have a worn posi I think I'll end up just replacing that.
How do I know what spline axles I have? That's important to know when buying a new posi right?

 

You can find that into in the following FAQ:

https://www.thirdgen.org/forums/tran...-10-bolts.html

BTW, listing the year, make and model of your car is generally helpful.

JamesC

 

What?!?! you mean you don't just know all about my car??? Sorry about that. It does make sense doesn't it. I've looked at that thread and based on the fact that it's an 83 TA I've figured that it SHOULD have 26 spline axles. But since it's a 27+ year old car and I've had it for 7 months of that time, I figured I should learn how to tell for myself what everything is in case someone changed it on me. Although seeing as when I got it even the vacuum lines seemed original I don't think anyone did much to the car in all that time. (The vacuum lines crumbled as I replaced them...SCARY!)

 

If you think that the rear end might not be original then the only way to sell what axles are in it is to remove one and count the splines. You must know what axles you have before getting a differential. You also must know what the gear ratio is.