I got a 91 TA rear bumper cover with gfx's. Its going on a 89 Formula, will I need the bumper under the cover froma the 91 or not. The bottom is too low so I cant fit the screws on the underside of the bumper. Also will this cause the bumper to look like poop, and the lines to be too wide between the car and the bumper?

 

You will need the stel bumper and the honeycomb from the 91-2

 

You will need the steel and mesh underside so the plastic pop rivets will pop in--but it isn't totally necessary. I put a 92 rear bumper w/gfx w/o the steel underside and it looks fine to me.
Here's a rear pic of my 86.

 

So you have a 85-90 Firebird originaly w/o gfx's like me. And you just put the plastic bumper cover w/o anything else other than the original reinforment bar and plastic junk to protect the car, and it worked fine? All I took fromt he car i got it form is the outer plaster parts which I just got painted and will be on the car asap.

 

i did the reverse swap, and i think the rear honeycomb/steel bumpers were very similar, and might work with either. the fronts are a good bit different. so you might want to try and see if it fits over the one you've got now.

 

No-I put the gfx on an 86 T/A. I just removed the old gfx, but I had to drill new holes for the 92 gfx(which you won't have to worry about).
Since I had the gfx already and you don't, you might need to get the rear crash bar as I'm not really sure what size the reg Bird crash bar is compared to the T/A crash bar.

 

Yeah the crash bar is too short on mine so I cant connect the bottom of it. So I guess i will go back to that yard and get it.