Same make of other van? The tops are made for specific makes.
I am sure it is possible, there was one member who completely rebuilt one. It is possible to use a RB top on an EB although you have to look at roof contour. The issue though is more than fiberglass and frame, have to think about the lift and canvas as well. I suppose it depends on the skill of the person doing the work and the level of project wanted.
Someone with more expertise may comment.
2008 GMC 3500 Quigley Weldtec 4x4 Savana SMB