Truck vers Car motors, I have found that the truck motor came with flat lifters not the roller lifter/cams that the cars got, and normally have taller gears, like 307s and 343s where cars like my 79 Caddy has 243 gears, so that would account for a lot of it.
I am building a car motor with the roller cam and lifter system, and do not plan on ever hauling a full ¾ ton load.
Darn they are doing the DOD correctly now.
Too bad refitting one will be so hard.
I take it as good news that I am on something of the right track.