A couple thoughts on taking out your seat frame. On a '49, if you take off the seat bottom and back, you will see four nuts sticking up from studs at the four corners of the frame. These bolt to the adjustor sliding mechanisms. However, there are also clamps at each side that bolt to the cable that operates the adjustors. This can be a pain to try to unbolt the cables and put back together. Instead look for the nuts that hold the adjustors to the cab. There are two at each end of the two adjustors, (eight total). They are under the front corners pointing down and behind the cab/seat frame (the welded in sheetmetal part) in the rear pointing towards the box. These rear ones are between the gas tank and the sheet metal frame. If you remove these bolts the whole frame plus the adjustors will come out. Note that you need to move the seat to the forward position so that you can tip it back to clear the front studs and then move foward to take out the back ones. Good Luck.

1950 Chevy 3100
261, 4 speed
Purchased 1977

1964 Pontiac Lemans Convert