I rebuilt my Starter about 3 months ago and the screws that holed the Solenoid in are Phillips head and all 3 stripped out when I tried to remove them. Even with me using a hand impact wrench.
I had to drill out the heads to get the solenoid off.

So not being able to get the solenoid retaining screws to turn would be a major reason someone could not change the Solenoid on the vehicle.

I am not sure where people come up with the names for stuff that the do but the cutch mentioned on the Starter is commonly called an over running clutch.

That pinion/overrunning clutch on mine had a what looked like a Bosch part number on it.

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84 300D, 82 Volvo 244Gl Diesel