Fan spacer size?

73AbodEE said
cast aluminum uses a 3" deep pulley and the iron uses a 2 11/16 pulley. I shoot for 1" away from the radiator

That's only 5/16" difference between the two spacers. We're talking about 3" vs 1 3/8" spacers. (That's 1 5/8" difference) I don't know if mine was changed at some point, or if it is the correct one.

My pulley is 3" (alum water pump)