I have a GMC 336 that I'm using in a 1958 GMC 3/4 ton NAPCO I'm restoring. The engine is in the shop now. Anyway, the guys at the shop called me and wanted to know if I had an early, mid, or late GMC 336? The block serial number is 33603131. I believe this is an early block based on the Pontiac 370. It also has completely dished pistons. Not the partially dished pistons. Block casting number is 530046. Just wanted some verification from someone "in the know" to make sure I'm correct before I tell the shop to order engine rebuild kit. Appreciate the help.
Cheers,
Craig
