Hey guys,

I need your help. A friend of mine has a '79 C20 Suburban and wants to change his rear brake drums. We looked at the Summit and LMC Truck websites (as they are more or less the best when shipping to Europe), but there are always two different diameters
a 13" and a 11-5/32" (or 11,156") size

which one is the right one for him?

thanks for you help