if it's a Chev, you have neg ground [pos on early GMC's], and yes the problem will be in the switch on top the starter, which was no doubt quite worn just thru age, and got a bit too much corrosion crud thru all your adventures, so stopped making contact - may be cleanable, may need replacement, but I'd bet the starter itself is not stuck

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics