I need a new proportioning valve and my local dealer has one for a Chevelle Wagon,
I have a Coupe, Disc's up front, drums on rear, the part numbers are different but how much different could the thing be, I realize that the wagon has heavy duty brakes but are they interchangeable
I have a '69 SS and want to change to the '71 and up Combination/Proportioning valve set-up

The wagon will be heavier, especially when loaded. Perhaps it will allow more pressure before it starts limiting.

If you have the ACDelco partnumber you can use http://207.74.147.153/internet/internetmain.jsp , click on the third icon and see the applications for that particular number. If you have the OEM number you can use the fourth icon to get the ACDelco number.

I know somebody who uses a combined valve (Delco 172-1350 and OEM 1257177) on a early Camaro with front discs and he is very happy with it. Hope this helps.

Rob