What's the difference between B and C model Calipers?

I just noticed my bleed screws are pointing downwards instead of up. If they are swapped to the other side, they'd be pointing upwards.
When they were rebuilt in the '80s, the shop must have put them on the wrong sides!

Regarding location of bleeder valve on caliper --

FWIW, bleeder valves in front calipers on KZ900LTD (twin front discs) are not directly on top. To bleed front brakes, FSM (supp) instructs removing calipers from fork legs and holding them with bleeder valve in direct upright position while bleeding air from the system.

Following the manual worked for me.

Interesting, I like to use powersportspro.com . Its just like buykawasaki but with the price list. I was just looking at buykawasaki and they show two different part numbers for the B-1 and B-2 caliper assembly for 77. Wayne

Yes, interesting indeed.

Buykawasaki.com has a new crossreference page where you enter a part # and it's supposed to show you all the machines that part was used on.

I have no way to double check those findings and was just taking them at face value.