I guess those are Huck brakes on front and rear. The same general arrangement except rears are larger, and have the parking brake mechanism. I know thats what are on 48-51 3/4 tons. Try these pages from the 48-51
shop manual. I hope this is helpful. Oh, good luck finding the parts as they are getting harder to find. I think the wheel cylinders/kits, hoses and such are available from the usual vendors, but you may have to get the shoes relined at a custom/truck shop. Good luck.
