since the leaf springs are located by a bolt head in a hole in the middle of the perches, trying to redo the ubolts won't move anything. 3/8" isn't enough to worry about. that's only 3/16" off and that could easily be caused by bushings or spring differences. :thumbsup:
2" seems to be the most common spacer size, probably because it allows for plenty of lug and nut space inside that dimension. I doubt you'd notice that half inch. :thumbsup: just make sure you get good quality ones like spidertrax.