Barry, I love the blue/silver of that truck. My friends had a 93 GMC K3500 SRW with a 454 4L80E in that combo.... Brings back good memories.
Glad to see them at least bolted on. Did you really have to push them on hard to get the nut with support bracket? Mine was SUPER tight.
I got the bottom two pretty tight then lifted up on the mirror. Got just enough to get the nut started. The base does match up perfectly with everything.