...which had to be reinforced and considerably reworked for the higher speed used in drag racing applications. The original use for these things was to scavenge the exhaust on a two-stroke diesel, it didn't provide any supercharging effect as originally used. The belt tensioner pulley had to be created and adapted, so naturally different builders put it in different places. Even some of the early specialty end plates had a separate piece to hang the tensioner pulley, then later end plates began to incorporate the attachment for the tensioner pulley. A handful of guys (the Surfers fuel dragster) dispensed with the tensioner pulley, putting the blower belt on by tilting the blower up at the rear, placing the belt, then setting the blower in place to stretch the belt. A number of MPC kits have the two-pulley blower belt but not that many teams ran it that way.
--Mark