I didn't even know the difference between an H case and a B case, let alone that there were B and H cases, until after I bought the B case. Seeing as I couldn't find any used H cases for sale and Strange lists them for what? about $350, I figured I'd stick with the 31 spline. I've been running mail order only shafts in the rear for five years now with out breaking one so... Granted, I'm moving from 33's to 37's but I've been running 27 spline D30 stuff and I'm losing some weight at the same time and I don't drive with my balls. If I start breaking, I can always redo but I'm hedging my bets given the way I drive. I know its pretty minor and I'll probably never make use of it but I like being able to swap centers front to rear as well.
I wouldn't know where to begin shaving the diff. Got any writeups? Again, I've been running a full size nine in the rear for five years with 33's and that's not where I end up hanging up.