My son an I just replace my 66 C20's tank.
I actually put the thank alone, then my son tied evrything together.
It can be done without to much trouble.
Watch out for the gas gauge wire.
Put the neck on loose and place the tank. Adjust the neck so it doesn't stick out to far.
Pull the tank again and tighten the neck, the put the tank in and tie it down.
Good luck and stay safe.