I understand that b110 5sp prices are expenive, but I would pay $1000 - $1200 for a new one from the factory. I think I may make some inquires in ZA for supply of one. Im guessing they are 60 series H pattern?. As for your repair, I think the cheapest option is find a second hand extension housing with the a rear bearing in spec. In OZ a second hand 56 series 4 sp can be had for as little as beer money if not free. Like I said before, I have a couple of spare 56 series 4sp extension housings, you can have for the price of postage. cheers
benny