Thanks for all comments and suggestions. I really don't wanna plug it, and dad wants to keep it original as it came from the assembly line so I'm trying to make him happy as well. It has NEVER leaked before this. The heater plug cap came off easier than I thought with no breakage or cracking, just slight persuasion.
There is 2 o rings under that electrical cap. International sells them. When mine leaked about 5 years ago I bought 2 o rings. Kept one for a spare. Have not needed it but its in the glove box ready to go. I probably will just plug the hole when it leaks again. I see no reason for keeping something that does nothing.
Speaking of 2 O-rings...After reading this tech article on this site Firday afternoon:
http://www.oilburners.net/forums/showthread.php?46363-Fuel-heater-O-ring-replacement
He is very detailed and gave a part number for O'ring via International, etc, etc. I called IH Friday eve and had em get me 3, (2 for spares) coming from Atlanta will be here Wednesday.
Well I've been watching you-tube videos and decided to go take mine apart this afternoon, and guess what? It's different from his. Apparently his is a '93 and mine is a '92.
Mine is identical to the one in this you-tube video:
https://www.youtube.com/watch?v=M6ILnpNCxu8
Dude says there is 2 O'rings and points them out, one on the heater on the lower portion, and one on the upper portion. In the comment section of the video someone post 2 different Napa part #'s for O'rings, which I'm assuming they are 2 different rings? So guess the IH ones aren't gonna work afterall?