I am new to the 620 trucks been wanting one for a while but had been working on a 2000 single cab chevy. I now have a 73 620 with the manual tranny that needs a clutch. The truck also needed a fender repaired and while looking for it I found a 77 KC 620 with an automatic so Im wondering If it would be practical for me to swap the trannies put the auto in the 73. Would I have more/less power, would I have any drive line issues. Thanks in advance I am a noob to these trucks.