I need to know if y'all think I can swap raised tops on different year vans.

I own a 95 Vansura 2500 conversion van Explorer model. I've been slowly converting it into a camper. Recently bought a 75 G20 with a raised top that allows enough head room to stand up in.

I measured the outside of the roof gutters on both vans with a piece of string. They are identical. Do you think it could work???

Second question; the old top on the 75 G20 is sagging in the middle and I wanna get it pushed up some how so it sheds water instead of creating a mobile kiddie pool up top . Any on got any suggestions on how to fix this problem?