that sucks man, i blew my ke30 tailshaft in salisbury in front of a mates one time ages back,(i live 30 mins away)
lucky for me he had a spare one...or so we thought, the one he had was for a ke55 and had a different flange for the diff,
so we knocked out the unijoints and attatched the ke30 tailshafts flange, the unijoint was smaller so it was hell loose, so we welded the caps on to keep the joint in place
drove home at like 25k's an hour with many many noises, but it worked lol.
ps, how did yours fall out? did one of the unijoints break? were you going fast?
if the front unijoint broke like on mine and you were going fast that could end seriously badly, could dig into the ground and basically push the diff out of the back of your car, or flip the car depending, so glad i was only doing like 5k's an hour when mine broke