Does anybody know if any other GM cars share our same mirrors. Would Le Sabre or Park Avenue mirrors work, or am I stuck with the Bonneville.?

stuck with the bonneville as to bolt on another mirror

now if you want custom, the sky is the limit

I may be wrong but I think the GTP mirrors will fit. They look darn close at least, but I havent been able to look at one real good yet. I have been waiting to get one in our shop so I can see if the are the same cause I'd like to swap mine if they will fit.

there not the same. even though they look it.

for starters the top part of ours is taller than GTP'*

Dang, ya just had to ruin my hopes

So......do any other mirror'* fit.

no other mirror will just fit there, but with some work the sky is the limit.
one thing you can do is to fab some triangle covers that painted black, & then use 92-99 or aurora ones (my faborite).