Stop in for a cup of coffee

I think so 1 5/8? Karl would know for sure. Front and back are different sized for sure. Good time to add a petcock in the block where that plug is.
yeah, just replacing 2 big ones on the side... wanted to make sure they didn't change from 1 5/8 to 1 11/16 in like 1977 for no reason at all... well.. just to annoy me :) and didn't think bout a petcock