X-cab beds and standard cab beds are the same on 4x4's, they are a 6' foot bed. AFAIK, Toyota never made a 4x4 std cab w/a 7' bed(would be on the x-cab or long bed frame), and made 1st gen 2wd X-cabs(2nd gen style) w/a 7' bed, not sure if they made any 3rd gens this way. The other differences for the 2nd gen trucks was the 4wd beds had a wider wheel well flare to match the wider flare of the front fenders, and you still had the option of the JDM bed(outside rails) or the USDM bed(smooth sides).
If you are looking at a used bed for your truck as long as it is a 6' bed it will fit, regardless of which type of truck it came off of w/in the generation, and you can even swap beds between the 1st 3 generations(possibly the 1st gen Taco as well but the gas tank door would be on the wrong side), w/only slight alignment issues.
