I have been looking at taillights my self...I have a 1990 760 and it appears that the 88 and 89 are different than any others...FCP has them listed as 88 89 ONLY... I can tell you this... the 1990 740 and 760 are different but they WILL fit...the 740 tail lights are about 4 inches shorter but they will bolt right in

I just bought a 1990 740 16 valve for parts and looking at the nice lights on it I had to try, and they do fit...I did not try the lights but the plug was the same as was the bolt patteren. I have decided to keep the originals and sell the 740 lights...I could not clean up the 760's enough to feel good about listing them

I have not been able to find a picture of the 89 lights online to look at, but if I was looking... I'd measure the bolt patteren and lens, take a real good look at the connector and then hit the wrecking yards...I'm bettin SOMETHING else will work...maybe look at getting the connection as well and splicing it on so the earlier lights will fit?

Sorry I am not more help
Bret
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rust free in west Texas