I have been away for a few days now and thanks for all your help guys on this problem. Well back out in the garage to try all your suggestions. Good thing I have my waste oil heater out there. Temps down to low 30's this morning here in NY.
Just to get to these glow plugs and terminals is such a hassle (603 engine), plus all the wvo plumbing, I might take off the intake manifold again. Its almost impossible to test the GP wiring with it on. OK, back to work.