I am doing some light tune up work for my neighbor on his 77 Dodge van motorhome, (plugs, wires, cap, rotor, oil change) After doing all this everything was looking good until I shut it off to look underneath for leaks or anything out of the ordinary. I then tried to start it and nothing. No click, no nothing.I had started and stopped it about a half dozen times prior to this. The starter appears to be fairly new and all other accessories have good power to them it seems. I was wondering what happened to this thing. I need to get it figured out as I don't really want conflict with him or him thinking I messed something up. Anybody familiar with this type of problem and what it may be. Thanks In advance for any help.

does a 77 still have a starter relay?
Is it dead? neutral safety switch?

Can you find the starter relay? If it has the Mopar setup, you can jump across the large nut (battery) to the smaller one (starter)to check the starter circuit. Make sure it is in Park. It also wouldn't hurt to check all the connections to make sure they are clean and tight.

I stole this from Stumpy: hold the key to start and move the gear selector thru all the gears & see if it cranks. No go see if you have fire to the yellow "sol" wire to the starter relay while a helper turns the key to "start". At the starter relay pull the wire off of the "grn" terminal & ground this male terminal & see if it will start with the key.

Check the yellow wire on the starter relay for power when the key is on START position and check the other small lug for ground when in PARK or Neutral.

Thanks everybody it was a crappy neutral safety switch wire harness plug. It wouldn't stay connected to the sending unit in the trans. I just cleaned it up with some lacquer thinner and used some Ultra Blue gasket sealant around the lip of the round harness plug to hold it tight on the prongs.