Tonneau Cover Snaps and Zippers

I've been looking at Tonneau covers on ebay and there seems to be several different configurations in terms of number of snaps on the flap that holds the cover to the side of the battery compartment and the length of the side zippers.

I have a '74 B with factory shoulder belts that have the reels attached to the wheel arch. It has two dot type snaps on each side of the trans hump.

Do I need to look for a cover with four flap snaps and long side zippers.? Why do some just have the two flap snaps? I take it the ones with the short side zippers are for cars with the shoulder belts mounted on the rear cowl.

Thanks - Paul

dont forget the headrest style and wheel pucker.

I've got 3 tonneau's and only one fits my car.

They had the box type head rest (pillow?)
the flat style headrest and no headrest.

Some with the steering wheel and others
without.

I do think one of mine is for a midge since
it's notably shorter (bout 3" or so)

Good Luck!