[John Strenk]

Looks to be in incredible shape for a 66.

 

[John Strenk]

I was wondering if that is a GM bell housing in there now.

 

[John Strenk]

I don't know, I'll be honest.... I don't know what a bell housing is. Time to go to the googles.

The part circled in red is your bell housing.

This is a basic small block Chevy bell housing.

I think if you had a Buick V6 in there, your bell housing will have a similar bolt pattern.