I put a '96 3.42 posi disc rear in my GTA. My GTA unfortunately had the optional drums (deleted disc) on it. I haven't swapped prop. valves yet. It stops ok, but not as great as it should. Question is that I have a prop valve off a '88 GTA with 4wd sitting here. Should I just use it or get a wilwood or something. Money is an issue so I'd rather just use the valve that i have off that '88. The dealer said that the '91 4wd valve and the '88 4wd valve I have are not the same part numbers though. Will that matter? Thanks

 

The '88 valve will not work on a '91. You need GM part# 10164112

 

Thats the number they gave me. It costs $70.88 though. Why can't I use the '88 valve? Should I just go with the adj wilwood valve or what?? Thanks

 

I know 89 changed one of the brake line nuts, and I am sure they did more after that.

 

The thread pitch is different on the pre '89 (late '89) proportioning valve fittings. It won't fit.

 

I see. Thanks for the info. Guess I have to buy one now

 

or get one from the many parted cars here.