Do as scrubcadet10 says.
Get a 3/8 NPT pipe nipple 4 inches long, galvanized or black iron, a 3/8 pipe CAP and a roll of teflon tape 1/2 or 3/4 inch wide. Put 3 layers of teflon tape on the pipe threads (wrapped opposite direction from the way the threads turn into the block) Take a pair of...