Easy way to identify /6 from small block 904

I need a new 904 tranny for my '68 Barracuda. I recently found someone locally with a rebuit one for sale, but he isn't sure if it's for the slant 6 or the small block V8.

I've read that the starter mounts higher up on the 6 transmissions, but if you haven't seen both, is there an easy way to tell what 'higher up' is?

Thanks

Jay