They are made out of aluminum, do they come with a steel sleeve where the oil seal rides on the pulley. Under all the post I read I did not see anything regarding this. I was thinking the aluminum might wear faster then the seal riding on a steel sleeve.
ive personally had in my hands an RSM underdrive and an RSM stock sized and the ebay underdrive and neither have any 'steel' in them whatsoever. solid billet aluminum.
