will the doors interchange between a third gen firebird,ta or camaro my buddy needs a door for his gta but all i have are camaro doors dont know if they will work

Pretty sure they all fit.

They fit, just have to fill in and/or drill in new ground effect holes.

has anyone done this change before?i'd hate to sell the guy something that wont work or look right.

There are 3 areas to look at when swapping doors. As zride91 mentioned, the ground effects holes may or may not line up. The other thing to watch is the mounting for the little black triangle at the front of the door. The part that seals the window to the A-pillar. They aren't the same on all years. I've been dealing with mine leaking because I used a 92 triangle with an early 80's door. I recently picked up the right piece, I just haven't gotten around to installing/adjusting it yet. Otherwise, they should line up just fine.

The third area involves the power accessories. If you're replacing a power door(windows, locks) then its much easier to replace it with a power door. Manual doors can be converted, but its extra work.

The triangle near the mirror interchanges fine. You just need adjustment

82-91 used a 2 piece design, then 92 introduced a 1 piece design

All NOS replacements use the 92 1 piece unit

Not sure how they do that. I tried my original(92) triangle on an earlier door and I had to drill a hole in the inner door skin to get it to mount. I never did get it aligned properly. I found an earlier one at a JY and it fits a LOT better, but still needs some minor adjustments. The window glass also seems to be slightly different as my original glass now doesn't fit in the opening quite right.

Yes, Camaro doors will definitely fit his GTA. He will definitely need to drill new ground effect holes but the door will bolt up perfectly and the old ground effect holes will be hidden.

Just to note, this doesn't work the same for Trans Am/GTA doors on a Camaro. The Trans Am ground effects are taller than Camaro pieces and the mounting holes are higher on the door. Because of that, if you install Camaro ground effects on a Trans Am door, the top half of the old mounting holes will show above the Camaro ground effect piece. You could still make it work but you would have to weld up the old ground effect holes so they don't show.

haha i changed out my triangles and done some converting. I have an 83 z28 and i took the triangles from an 85 berlinetta, of course they are both very different as to how they are bolted in. SO what i did was get my dremel tool out (after i pulled all 4 triangles from both cars) and sat on the floor of my apartment and drew a line and cut all 4 at the same lenght just before curve of the triangle, then took hot glue and a couple small pieces of sheet metal (for support) and glued the good ones on the bracket for my car.. bolted them bitches in and it works PERFECTLY! no wind noise or leakage, holds the glass better also with no rattles. if you want more info how to do this let me know i can tell you.

Yes they interchange. As for the window seal and track there different types. Old style 82-84 mid year and 84 -92 and track type.
I put 91 camaro doors on my 84 TA, I purchased new(used) tracks and seals (new) because I found there are tracks with rubber and ones with foam. This is the area the window slides up and down in. The rubber ones get hard and break in pieces and also can let the window rattle. The foam keeps the window in place better but is a pain to take out and replace, I had to replace everything. I replaced my door skins so when the old ones were cut off I put everything new in.

I am doing a door swap from an '87 T/A to my '86 Camaro and also noticed the metal piece riveted to the door to attach the door panel is different. So far, I have knocked off both panels by using a small sledge and chisel to knock off the rivets and now I plan on tack welding the Camaro piece back to the T/A door. Holding the old plate against the new door, I can see where they both have the same holes from the factory but just used different ones to rivet the plate to the door.