67 C20 rear drum brakes.

[Still Haulin]

I know that this must have been brought up before...
Is there a difference between the rear drums on a 67 C20 that has 8 lug wheels but has coil springs instead of leaf springs?
My cousin has been told that there is and the ones for the coil spring setup are no longer available. Sounds hinky to me... There has to be a source out there that if given the needed specs, could get him the drums needed. Anyone know if there's a difference in the first place? Is there a good source to deal with on getting the right drum?
Appreciate any help or directions you can provide.