I'm looking at buying a 1988 formula 350 and have couple questions.
1.This car has manual windows and the door stickers match the dash vin, could you get a formula 350 with manual windows?
​​​​​​2.All of the engine harness has been cut out as it was converted to carburetor and has a/c delete box.It was also converted to a manual transmission so a parts car will give me everything I need.Will a 89 parts car but effective for restoration of this 88,I think 89 was the start of the pats key?Should I really hunt for a 87-88 5.7 gta parts car.My biggest thing is to have a/c heat auto and working original style cooling fans.

Yes, you could get a Formula without power windows. The Formula was considered the performance vehicle and could be ordered with minimal options. Approximately 20% of the the 1988 Formulas had no power windows.

As far as what you'd need in a parts car, that kinda depends on what parts you need. Which in turn depends on the degree of sodomy the car enjoyed in the course of its various earlier "improvements".

There are VERY FEW parts that are specific to GTA. Any 88 Firebird variant with TPI will have everything you need for AC, heat, and fans. You don't need a GTA for that. You'd need an auto trans one to get auto trans parts obviously, if that's what you want to put back in it. Problem then will be, the degree of control over fan operation that the ECM had, and whether you can recreate that somehow without it.

One more note, regarding the pats key, most (3/4s) of 1988 GTAs came with the security key. It is easily cut out of the system, so that should not be a big concern of itself, but will be more work. It became standard on all Firebirds in 1989.

One other thing to look for is many 1987 and 1988 GTAs, as well as some 1986-1988 Trans Ams, came with the optional digital cluster and optional HVAC control unit. The Formula never had this option. The digital cluster used extra sensors so there would be several more different circuits that your Formula would not have.

This car is missing the 5.7 and 700r4 transmission all of the engine bay A/C components and relays on drivers side.The auto brake pedals were swapped for manual pedals and has hole cut in floor for shifter.The center console is a 4th gen one and definitely not my taste.I came across a 87 gta with a 5.7 but the A/c is on drivers side.So from what I'm seeing a 1988-92 would give me the most parts for the money.The only specific parts I'll probably have to find is the formula hood,formula wheels and center console top for no power windows or mirrors.I believe the 5.7 computer is still in the car not sure if there's a difference on computers for 5.0 tpi and 5.7tpi

An 87 wiring harness will be fairly specific but 88-92 engine/trans will be good to use. 88 would be best due to cold start inj, t-body and a few small things.
89 had changes then 90-92 were pretty much the same