It runs! Thanks for the advice Jake. I cleaned the starter connections and the ground (all dirty). It still didn't start. I was walking around the truck half checking connections and put my hand on a plug just by the driver's side firewall and adjacent to the master cylinder. When I touched it it almost came off. I fiddled with it and got it reconnected. The engine immediately cranked. About 6 cranks later it started, ran rough for a few seconds, then settled into a nice hum. Thanks to everyone for their help and suggestions!

 

Good stuff man glad you got it. It's always the stupid little things

 

Starter motor parts usually have a deep boss with an 'O' ring where they fit into the cases so they're a good interference fit - gentle application of a screwdriver behind the motor where it slides into the casing should ease it outwards.

 

I removed my heat shield in 2007 & it's been off ever since with no problems.