that's cool i didn't know the low humps unbolted. i never looked that close. i have taken several of the high humps out all mine are those. i had a 66 with a low hump it was round. the others are square and flat don't know if they are actually higher ot just bigger across the top. if they are interchangable how could you tell if someone unbolted one and bolted in another? on my 63 it had metal around the windows, bought one from another truck and it didn't. oh well i'm not that picky. hr