I have a RT-68 in my M38A1 and the seat will not fold up - not enough room. But the seat can still be removed pretty easily if you need more space for cargo. Wes is correct, if possible mount your radio on the left to balance the weight evenly - my Jeep is developing a sag to the left.
The radio is functional and I have a spare radio chassis for parts. Tubes are still available. I don't operate it much but it stays on the Jeep and takes all the vibration pretty well. Solid construction!