Reply to "ZF gears jammed upon reassembly"

That's a rare failure, CB; mostly, the forked end of the Veglia angle drive (that mates with the little tongue on your gear just above the thin spot) shears. You're lucky: I've seen a loose speedo gear driven into and through the cases like a blunt nail!
An un-fun ZF-thing a friend found: after digging around inside his ZF, the setscrews that hold the shift forks to the internal shift-shafts should be red Lock-tited and peened, as you lose control of shifting if the forks slip. My friend used 'liberal' quantities of Lock-tite on the setscrews, which ran down the shafts, into the guts of the transmission and froze the entire assembly solid! He had much trouble even getting the thing back apart....