Assuming you are removing the original motor from your '46 there should be few issues dropping the 270 in place. You many need to change the front mount on the 270 to the earlier type, but externally there are few differences and those are mostly in the accessories.

I'm not an expert on cranks and flywheels for these things and can't speak to what you may find there.

I have a later 270 in an earlier truck and my biggest complaint is the BC GMC logo on the valve cover. Because I don't have the earlier oil fill tube I can't easily swap to the early GMC logo. Some day I'll solve that problem.


1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...