I'm having difficulty in seeing how dropping the transfer case, which is where the driveshafts connect, would improve the front driveline angles. As the t-case is lowered the whole engine/tranny/t-case package will be rotating around the front engine mounts. Therefore as the t-case is dropped the u-joint angle at the front output would increase, if I am picturing this correctly.
Another note: I don't think the t-case drop mod will work on early FJ60s since they have a different style crossmember, one that bolts up between the framerails.
It drops it down perfectly with good angles, fixed the front and rear driveline vibrations without going back to axles at all. On the FJ60 it wouldn't be the same; but he included both sets of brackets in this kit for the 62 auto and 60 manual and was the only part left out of the kit that wasn't used.