1972 Chevy C10 Perplexed

[1963hoss]

Hello. I bought my dream truck a couple of months ago. It is a driver with only small cosmetic things to replace and minor mechanical things that need work to bring it back to the original condition it was as new. I have two pressing problems maybe someone can help me with. I cannot get the a/c blower to work on high. It was fine until I serviced the a/c and then the relay went out. I replaced the relay. But now the blower only works in low and medium. All the wiring and the switch checks out ok for juice. I looked at the resistor and the motor and they seem fine. I am stumped. Next I really would like to locate a original jack for it. They are hard to find. Does anyone know where I can locate one in working order? Any help or ideas would be appreciated.