If not mistaken the EForce kit for the LS3 #1598 already had the 3.5 pulley(at least mine came with a 3.5) the larger pulley was the #1597kit for the L99. Running the 3.25 pulley here now and mid 650/620s with the other work done on 93. Going to guess 548/520 with a 3.5. Best wishes.