Originally Posted by 08XLT4x4
since when does a wheelbase have anything to do with a fuel pump?
In this case, it does.
Each of the three nominal wheelbases (112", 118", 126") uses a unique fuel tank (16.5, 20, 19.5 gal). The 112" and 126" reg and supercab shortbeds share one pump assembly number but the 118" reg cab/longbed takes a different assembly.
Even though the actual pump itself is probably the same for all 2001 4.0L's, the intank assembly is different on the 118" for some other reason. Depth of the fuel pickup would be a good guess.