I have a quick question for ya. I have a 1989 Trans Am with the 5.0 Automatic. I am attempting to figure out what kind of transmission I have in my car for future mods/or replacement. While you might not be able to go "oh you have this", I am just looking for a way for me to find out.

Onward to the rear question(s)! Reading the posts on this board has bludgeoned into me that a 10 bolt rear can't take high hp. I'm not looking for real high hp numbers (yet), but I am looking to doing some mods to my car (shorty headers/cat back, msd ignition as the main ones, maybe a new intake manifold, head and cam). Should I be looking at getting a new rear, or would my 10 bolt be able to handle this? (I just dropped in a new Jasper 305 TBI, not sure on the ratings for it though)

My second question makes me feel kind of stupid, but what gear ratio would most suit my needs - it will be a somewhat tuned daily driver. Sort of a spin off of that question, is it possible to make my non posi rear into posi by installing new gears, or do I have to replace the entire rear?

 

Trans is a 700-R4. It's the only one that was used in these cars from 83 or so, on up.

No need to worry about the rear, as long as you don't abuse it. A 305 TBI isn't going to tear it up without doing stupid stuff like long one-wheel burnouts and other destructive behavior, such that it doesn't matter what motor or what rear it is, you'll still tear it up.

For gears, 3.23 or 3.42 work pretty good for a mostly stock 305 TBI.

You can change out just the carrier without touching the gears (except of course to bolt the ring to the new carrier), to get posi. But if you're going to do gears, best to do it all at once.

 

How durable is the 700-R4? I know that some stupid things have been done in the car prior to my purchasing (which is mainly why I needed to drop in a new engine), and I'm a little leery about the transmission (my mechanic said its starting to go, but I haven't noticed adverse effects yet).

You mention changing the carrier and bolting rings to a new carrier - I have absolutely no idea what that means. Skipping over that part of it, what carrier is recommended for posi (of course I would like the limited slip).

Sorry to sound like I don't really know anything about cars, but its true. I know the basics and theory behind everything pretty well, but beyond that I'm quite lost (specific part names and how to put it all back together)