auxilliary fuel cap 1 3/4"

[SKELLEY]

I have a 71 lwb k10 with three fuel tanks. I finally got the main tank to quit leaking when full and turning by the addition of 2 additional gaskets at the cap. When I got the truck it had no keys to the fuel doors for the obviously add on tanks on both sides. I finally took off the doors and found one cap to be in poor condition and the other missing. These are 1 3/4" with center clips to hold them on. I would like to restore these tanks and put them into use but I will either have to change the fillers with limited space or replace the caps shich I cannot find. Anyone have any experience, thoughts and or fuel caps for sale?

Thanks, Sean