The neat thing about Ford solenoids of that era were that they were very conveniently located near the top of the firewall and can be easily triggered manually if needed with a big screwdriver across the leads. (And hope you don’t get electrocuted in the process.)
Contemporary GM solenoids were integrated into the starter motor and were a real pain to get to. Certainly not impossible to do the screwdriver trick but far less convenient with needing to crawl around on the ground and all. Being located right next to the exhaust headers also meant they were easily susceptible to heat soak problems which would cause a failure to activate - especially if you have a hot-running high performance engine. It was actually a pretty common and easy mod on those GMs to use a Ford solenoid and bypass the one on the starter motor.