Go to
http://www.brickboard.com and click on the 'features' pull down menu, click on the 700/900 FAQ. In there you will find a wealth of info on your car.
You can use a generic GM blower motor from a mid 80's GM car. I got mine from NAPA for about $20.
As for the fuse, I had problems with my old 740T. Two of the wires under the fuse tray overheated and melted a realy carrier. I also removed the lower left hand elay, for the power windows and aux fan, adding a 'Y' jumper so they always worked.
Read up on the electrical section. You can pull out the fuse/realy tray and flip it over to work on it.
You also need to resolder the fuel pump relay, the large white relay on the left side of the middle row. Pop it apart and resolder the connections.
I've had many of my postings added to the 700/900 FAQ. I think we need one for here on the various MB's.