Before the GMC 228 in '39, I think, GMC used Pontiac and Olds flathead sixes Ellis made multi carb intakes for lots of trucks and I'm pretty sure they made them for the these. I have seen them for later GMC and International sixes even the BIG GMCs.
Almost all of the after market intakes are aluminum and with the easy availability of TIG welders modifying one is pretty easy. Thank God for Eddy Edmunds, he made something for everyone. An intake is easier to make fit than a head but I've seen some two piece CNC aluminum heads for other flatheads so it's about how bad you want it and your checkbook. What ever you do that old flat motor has a cool factor no modern engine can touch.
