Here's what I can tell you which probably wont be much help. I have owned two 8660's and both of them came with Bostrom Viking T-Bar seats. I don't think that was the original configuration though. I have some literature somewhere that I can scan an post that shows the stock setup. I believe they were mechanical suspension of some variation. There are some brackets welded to the back of the cab that appear to be for height adjustment. I was lucky to find a NOS T-Bar mechanical seat
http://s1366.photobucket.com/user/M...g5_zpsf497fd67.jpg.html?sort=6&o=167 that I will use on the drivers side that is in real nice shape and another one that is used but in great shape that I will use on the passenger side. These seats are relatively small compared to modern truck seats but with the T-bar all the way back my knees are sticking up in the air. The other problem I have is, after painstakingly restoring the 22" steering wheel that came on the truck, it is simply too big. My hands would be hitting my knees. Luckily the truck came with parts from two other trucks, including 2 20" wheels so I have already begun my second steering wheel restoration.
