My engine is not cranking over like the starter is bad?

I Have a 1984 F150 I have received from my Step Dad when he passed away several years ago. I have ben restoring it between deployments and ahve the same problem several times.
The engine refuses to start. It has appeared to be a starter problem and replacing it has cured the problem in the past. I recently replaced the starter only to have the truck start once then not start on several attempts later.
The starter has been replaced twice in the last couple of days with the same results. A large load on the electrical system and lugging of the starter until it refuses to turn or even make an attempt to start. The previous starter was tested and it spun the first test then locked up after that. It ws VERY hot when I removed it from the vehicle. The new starter does not get hot but still will not start. The battery is less than a year old and check's out good. When I try to jumper the starter solenoid it just chatters and the starter does nothing.

Yes the starters are the same brand - NAPA Supreme - I had a problem after I installed the first starter about 4 months ago - The starter refused to shut off and I could not shut off the engine. I disconnected the battery cable then reconnected the cable and the engine started and ran fine after that. I have been told that it could be a faulty relay, soleinold or ingition switch. Also is there a seperate ignition relay other than the starter soleinold. The manual I have calls the starter soleinold a relay?

The soleinold just chatered when I tried to jumper it from the positive input side to the exciter post. The starter did nothing.

Thanks