it should fit physically, however the top may not be setup for the proepr angle of the cab... i know that the 84-88 cabs are different between and excab and a standard cab due to the angularity of the rear window.... i would say go see if you can check it out... would suck for someone who isnt there to say it will fit, you buy it and it doesnt fit....
That shell seems to have a slight forward 'rake' on the leading surface. This might well work on your '01 XtraCab. In the 1995.5 - 2004 generation, Regular Cab rear cab walls were pretty much vertical, and XtraCab rear walls slanted / angled forward.
... But I don't know how well the angle on this shell might match the angle of your rear XtraCab wall.
Rail to rail on pickups and tacos: 57 inches. Both beds are 6 ft long . The front angle does look pretty extreme on it though. It looks like he had to set it back an inch or two and could not rest it on the front rail. Don't Tacomas have an even more upright cab angle than pickups? I would check it out in person.