question regarding a camper top

On a 2001 Taco, will a camper top for an access cab fit a regular cab? I'm worried that the contour of the back end of the cab won't allow it to fit.

 

You are correct ... The Regular Cab rear wall is vertical; the XtraCab rear wall slopes forward. Some manufacturers contoured the front edge(s) of their Tacoma canopies / shells to match the angle of the rear cab wall. Some didn't. Some 'split the difference' with a slight slope on the front.

So it depends on the particular XtraCab topper. In the worst case, the forward-sloping XtraCab shell will butt into the Regular Cab rear wall, making fitment almost impossible. In the best case, there will be an odd gap that narrows from bottom to top.

 

It fits. I have an X-cab camper on my single cab.