hmmn.. just got off the ph to the mechanic and relayed your thoughts - and he seemed to think the transfer case bearing was a chance. He said that normally when you drop the shaft out, you can unbolt 2 bolts, rotate it by hand and get to the other two, except he said that he couldn't turn it by hand, it was too stiff.. and the GTR shaft was actually fouling at the end of the transfer case (against a switch and a bracket that couldn't be bent back any more) His concern was that to change the bearing in the transfer case he had to drop the gearbox out of the car.. ($)
He also said that when he ran it with the shaft out the transfer case output was spinning true, but it was a bit hard to tell for sure. The bearing might have seized rather than collapsed, but there is no play with the new shaft in, but it goes spastic when spinning!!! ARGH!!!
<sigh>