Ok im at my witts end with trouble shooting this issue. Hoping someone can help me here. The reverse lights on my 87 gt do not work at the moment. I have confirmed it is not the wiring and have confirmed by manually depressing ball on the new switch that it is not the switch. Jumping the harness and pressing the ball on switch the lights will activate. Is there an adjustment on the trans to make the lever that depresses the ball on the switch contact the switch again. I'm sure this is my issue but I'm not sure how to rectify the issue. I did see in someone's old post that they used a Dremel tool to grind a part but if I need to go this route I need some better direction than was in the post. Thanks in advance for any guidance

There is a slider in the trans that pushes that ball, and activates the switch.
I had a similar issue with a Getrag that I had, but it also had shifting issues and wouldn't "latch" into reverse. Had to be held, or it would jump out. Made the reverse lights kind of "hit or miss".

One of the local guys ground the shoulder of the backup light switch down just a little at a time until the switch worked so that he didn't have to do a teardown on the transmission to repair the part Raydar refers to. He said he had to trial fit multiple times and also to be sure that the seating surface was perfectly aligned all the way around.

Thank you gentlemen. This is helpful and gives me a place to start. Might have to ask a buddy of mine to do some milling for me.

Good Afternoon Gentlemen. I finally was able to get my reverse lights working so I wanted to let you all know what my solution was. my Friend with a metal lathe cut off 30 thousandths from an ACDELCO Part # 14047186. (rock Auto has some back in stock as of 1/14/23)
there was a seating depth issue had was not allowing the pin in the trans to depress the switch ball to activate the reverse lights. cut down the bolt surface and now works like a charm.

Hope this helps Others
Brian Bender
87 Fiero GT W Getrag 5spd Trans

Thanks for the update!
It's always useful and appreciated when we can hear what the ultimate fix is, for an issue.
(Gotta love that GM QC.)

[This message has been edited by Raydar (edited 01-14-2023).]