OK, some good ideas now. I checked for power at the glow plugs, with a test light. All had power with the glow plugs activated. I have grounded the relay & had power on the output of the relay (again, testing with a test light). Possible I am passing voltage, but no amps through the relay? I can easily bypass the relay & retest. Remember that I removed the glow plug card & grounded the relay & that the glow plug system has been converted to 12V. The whole thing with the plugs being wet after cranking is making me lean towards a glow plug issue. I brought all the old glow plugs back with me & bench tested them. All were cherry red 10-15 seconds after applying voltage to them.
Plenty of fuel, at least to the filter. Compression loss seems to be unlikely. The truck ran fine last time I drove it & it sounds normal when cranking. I considered the possibility of rodent damage, but I see no reason to suspect anything at this time.
I'm going to take our wrecker down Friday night & bring her back on Saturday. I plan to try a few things before I tow it home. I would much rather drive it back than tow it.
I will check in tomorrow, before I go. Just to see if there are any last minute words of wisdom.
Thanks - Darren