Barracuda backup housing #2936020 and pr of lenses #2606824

Barracuda backup housing #2936020 and pr of lenses #2606824

I get what you are saying by "shorter"! Thanks for that. So using that theory, this would be pass side. And I believe this is the shorter one. I've heard that there are actually 3 different lengths.
Pics are of NOS one for reference

mvh said
Could it be a "short" housing from 1969?

The way I tell which side it belongs on is by looking at the outside rim at the points adjacent to the screw holes (that is, straight horizontal on center). One side will be slightly shorter than the other — that side is the inside. But it's too subtle for me to tell in your photo.