I'm seriously looking into ordering one of these too! Currently set up with an H41 with 4:1's in the splitcase and 5.29's in the diffs netting about 102:1. With the addition of the BB, I'll be at 279:1 with more gearing options as opposed to just one deep t-case gear. Question to the 40 series crowd: I learned that with the set up in my application ('81 BJ42), the BB adds about 8-1/8" in length. The fuel tank in '79 and later models have the tank underneath the body therefore may interfere with the install. My H41 trans is the short style (no spacer) btw. Unfortunately my rig is in storage and I can't creep underneath it at the moment to verify possible space issues. I've heard of some guys installing Marlin's Toybox and moved the engine forward. Can anyone with a later model 40 that has the gas tank underneath the body, and keeping in mind using a short style H41 confirm if adding 8-1/8" will cause issues?