1982 kz550 - a3/c3/h1 differences???

I just purchased a 1982 kz550 to fix-up and ride. I joined KZrider and would like to know if anyone can tell me how to tell what model bike I have.

Also, I need a fuel tank (this one is rusted thru). Is there a larger tank that would fit this frame? If not where can I get another stock tank CHEAP???
(around 50 bucks would be ok local cycle salvage wants 120-150)

THANKS!!!

Larger as in sheer bulk or fuel capacity?

If it has an 18" back wheel and drum brake on the rear, it's an A (standard).

If it has a mono-shock rear and two disks in front, it's an H (GPZ).

If it has a 16" rear wheel it's a C (LTD).

If it's actually an 83 model and has shaft drive it may be an F (Spectre) or M (LTD shaft drive).

I find tanks on ebay pretty regularly for $50 to $75.

I'll see what I have around here that's in good shape.