have tried everything in book , keeps running (diesels) after i shut it off , have to let clutch out to stop motor ????

 

sounds to me like the ignition is malfunctioning.

 

You can check that the ignition really stops with the key off, but even when it does, old carburetor cars do that. Various measures were put into place, mostly involving solenoids on the carburetor that cut the fuel off more completely. If I had a 1980 and that was the only problem with it I'd just stall it out like the OP is doing. Won't damage anything.

 

Replace the ignition cylinder or check the car's relays.