I'm trying to figure out how to open up the oil filter canister on my 235 (58-62). I took out the top bolt- but the top doesn't budge.

Is it supposed to rotate, or lift straight off? I tappend it all around with a rubber mallet, but not seeming to make a difference.

Truck has sat for years, so i'm sure its stuck- just not sure which way it "should" come off.

thanks!
Ben