I've never worked on a rear end before but I am fairly mechanically inclined. I do all my own repairs beside transmission work. How difficult would it be for someone like myself to replace the differential and install a new gearset? Can I use a gearset from any year (82-02) in my 82 trans am? Is there a big difference between 3.42 and 3.73? Do I need any special tools to do the job? I have 3.73 (stock for 82 with LU5 WS6) and want lower highway rpm's (3 speed tranny).

 

it's not hard, it does require a bit more thought than some people want to give it and it does require some specialized tools most people don't have, like a in/lbs dial type torque wrench, indicator and mag base, 0-1 mike or a dial caliper, 2-3 depth mike or pinion setting tool, press and pullers for the bearings, plus a "special tool" for holding the pinion yoke. the gears will be a direct swap depending on what carrier you have. best bet would be to swap carriers too and up grade to 28 spline axles.

 

Yea, don't just add up the cost for the ring & pinion. Go ahead drop another 100 plus on the refresh kit, and another 200-500 on the tools...
...and if you want to get a little fancy add another 300 on cover supports, and carriers...did 'ede' mention the other 250 for the axles you would need for that upgraded 28 spline carrier

Ignoring the dudes tring to get you to upgrade to a 2000 dollar 9" or 12 bolt is tough also. If were not talking 400+FP willie standing launches than don't worry about it.

The hardest tool might be the shop press since they can weigh in at 200 pounds, and good luck finding one at your local hardware store. (The guy at Homedepot looked at me funny when inquired)
However I got lucky, and had a tool show - show up in my county for the weekend last summer. Saved me a bundle in shipping!!!

You can do it, just like 'ede' said; it takes some serious planning & an untapped VISA or MC.

Ron

 

If I was you, and all I was looking for was a better highway setup, I'd ditch the POS TH200 and put in a (mabye not quite so POS) 700 from a later model, rather than slowing the car down even further by nutting the rear end gears. It's not hard to find all the parts to do a perfect conversion with no rigging or "mismatch" items (like the shifter indicator and stuff like that).

 

i'd have to agree with RB on this one.. 373's are great street gears provided you have a transmission with an overdrive.. i'd look into finding a 700r4 for a decent price and swap that in rather then trading proformance for gas milage and downgrading your car in the process, plus after all the tools and all it may even be cheaper

 

I replaced a 200C with a 700r4 in my 82 Z-28.
Best move I ever made. I have a lower 1st gear ratio and the highway rpms dropped abt 900 RPM.