g741.org

http://www.olive-drab.com/od_m37_heater.php3

In case anyone uses these instructions before installing an M151 heater in their M37. Be warned, the instructions mention buying 1/2" NPT pipe threaded nipples, etc. This is incorrect. It should be 3/8ths" NPT pipe thread, not 1/2"....

3/8ths" pipe thread gives you an outside diameter of about 5/8ths inch, which is what you need. 1/2" NPT has an O.D. of about 3/4" which is too large.

I almost bought the wrong items today at NAPA because I listened to what the instructions said. Good thing I took a look at the plugs on my truck's engine beforehand. I knew right away that 1/2 in pipe thread is too large.

It was wise of you to take the plug with you. Inaccuracies can sometimes be found in the best thought-out instructions prepaired by professionals. Whenever possible I also take anything I can to help in selecting the correct part or object and thus avoiding the dreaded second trip to the store. Good move Nick.

Merry Christmas, see you next week.

Carter;

Thanks and Merry Christmas to you and yours.