trying to make some ground on my 68 bird.i pulled out the subframe and it looks pretty banged up.

my question is what subframes will work as a replacement?

i have heard that 67-69 camaro and firebird are the same frame although suspension is a little different.

i have also heard that a nova subframe may work 1968-1972.

does anybody know for sure?

You have the basics correct. The A-arm/bump stop differences are what you have to look out for - they need to either match or use aftermarket control arms with multiple bump stop locations.

'67 Firebird/Camaro. Rubber bump stop is on the frame behind the spring pocket. Welded reinforcement point is on the control arm.

'68 Firebird/Camaro/Nova. Rubber bump stop now on the control arm at the rear of the spring pocket. Reinforced "hit" point on the frame behind the spring pocket.

'69 Firebird/Camaro, '69 - 72 Nova. Rubber bump stop now on the front of the control arm - hit point on frame in FRONT of the spring pocket.

'70 on up Firebird/Camaro and '73 up Nova are 2nd gen subframes and don't fit. All other Nova "corporate twins" match the same year Nova characteristics (Apollo, Ventura...)