I have read the tech articles and done searches, but still have a couple of questions. Pretend I know very little about working on rear end, because it's true. Basically, I currently have 3.08 gears and want to go to 3.42's. My mods are posted below in my sig. First of all, should I just have new gears installed, or would I be better off also replacing the posi unit and axles while everything is torn apart. I see where the takeoff units from the 4th gens can be bought fairly cheaply, but will I be gaining anything over my stock unit? Also, what is meant by a "3-series carrier?" Also, if I do go with a 4th gen posi unit, I understand I need to switch to 28-spline axles. Where can I buy 28 spline axles for a 3rd gen? Next, I have also seen fairly good deals on ebay for Eaton posi units. Are these that much better than the 4th gen takeoffs to justify the added expense?

Sorry for all the stupid questions, but what I basically need to know is how much of the rear end should I upgrade when changing gears, and then, what do I need to look for to be sure my gears, posi unit, axles, and so forth will all match (ie: will 4th gen gears work in a stock 3rd gen rear)? I absolutely plan on having the work done by a professional.

Thanks,
Eric

First off, 4th gen axles will not work in a 3rd gen rearend. the 4th gen ones are 2 in" longer. Second, the 4th gen posi units are not much better if any over the 3rd gen ones. As for rebuilding your stock rear, it all depends on the miles on it and what you plan on doing with your car afterwards. axles dont need to be replaced if nothing is wrong with them and you dont plan on drag racing every weekend. If yo uhave the money, then replce the gears, get a complete installation kit and buy a new posi unit.

Yeah, I don't plan on racing it very often, I just wanted to get a little quicker acceleration on the street, and I figured going from 3.08's to 3.42's would help out a lot and let me use more of the power my engine is making. There doesn't seem to be anything wrong with my rear now, but somebody told me the 4th gen posi was built better, so I thought I'd go that route as long as things are going to be torn apart. If it's no better though, maybe I'll just have the gears/bearings changed and call it good (I also know I need to change the speedo gear in the tailshaft).

Eric