I have searched and found the bulb is supposed to be a 1156. The 1156 is not the bulb that is in either of my Trans Ams, and the 1156 would not even fit in the reverse socket because it has a round base and the reverse socket will only accept flat base bulbs like the tail light and DRL bulbs.

The bulb that just burnt out in both of them is a 3155, and I cannot find a 3155 anywhere. Has anyone with a Trans Am replaced the bulbs in their reverse lights? This is annoying me.

 

You should be able to use either a 3157 or 3156.

 

After searching for hours, I found that the 3156 should work but I put a fresh one in and it doesn't work. I think it may be the socket. Anyway this thread is here now for people that are searching. The 3156 should work in place of the 1156 bulbs the lighting guides tell you to get.

 

i bought LED 3157's and they work fine