A friend of mine has a 1985 TA he is parting out. It has a Posi rear with 3.23 gears. I currently have a 84 firebird with open rear and 3.73 gears.
Is it worth the brake swap for the posi rear?
Is all I need a prop valve and some ebrake cables?

Any help is welcome

if you can get all the parts from that car Id definately say it would be well worth it for the posi and the discs. youll need the rear the ebrake cables the prop valve and the master cylender because it pushes more fluid for the rear discs. You will also need to swap speedo gears when you do it because it will make it read incorrectly. Goodluck with the swap and have fun with your new found glory of two black marks instead of one.

Scary thing is, my 84 bird is a 2.8 V6....and I DO leave a black mark

You don't need the master cylinder. The J65 (4 wheel disk) m/c has a larger bore, true, which allows for more pedal feedback when braking. People complained to GM that the brakes were too hard to push. (They probably shouldn't have bought a sports car.) GM said that the J50 (disk/drum) master cylinder could be installed to make the customer happy.

Definately need the prop valve, though.

And keep in mind the 82-88 rear disc recall. The rebuild kit is very cheap through gmpartsdirect.com. Here's a message that'll help you out! https://www.thirdgen.org/techbb2/sho...threadid=78725 I put the '84 3.73/posi/disc rear on my '86 2.8 (3.42/open/drum). How'd you get a 3.73/open/drum? Did you grab it from an '84 Camaro HO, or a 4-cyl f-body?

Opps my bad 3.42 I ment not 3.73

The brake swap is definately worth it; I had more fun braking then going! Although; get this- I spent over $600 putting that rear behind my car. New brake hoses, rebuilt m/c and calipers, new e-brake cables, http://www.por15.com super starter kit in semi-gloss (great stuff!!), axleshaft bearings & seals, caliper bolts, and the V12 injector from http://www.brakebleeder.com - great tool!

Luckily your friend's car is probably in better shape then the junkyard car, so you probably don't have to get new calipers. But find out if he had the recall work done (recall was only for 82-88 with manual trannies); if not, pick up that rebuild kit from gmpartsdirect.com . The directions for a caliper rebuild are in the GM Service Manual from http://www.helminc.com , and they're also in the cheaper 82-92 Camaro/Firebird Haynes manual (found at pep boys or similar or even http://www.haynes.com ).

Well he has only had the car a couple months...he got it from a friend of the family..He thought it had minor damage..Turns out the front subframe is bent, so he is parting it out.

So we have no clue what recall work has been done. I am just slowly parting it and putting what I want into my car


EDIT:
Oh his is an Automatic, mine is a std. There going to be any issue there?

And OH I saw you broke your Posi rear from a 84...is the 85 still prone to easy brakage? IE should I make sure to have another rear laying round?