Remnants of a shift knob?

My boat's current shift knob is interesting. It is a male threaded knob that is aftermarket. I ordered a plain wood shifter knob with a parts order a summer ago and was immediately confused when I tried to replace the knob.

It dawned on me today that what I am looking at is the aluminum insert of the old shift knob? I have looked thru a bunch of old posts. All the shift knobs I have seen on these controls look like a normal female threaded shifter knob. This would explain why only this remnant part of the lever is corroding in that manner.

Before I tried to file flats on the base, I would appreciate some expert advice.
Currently my boat's shift knob threads into these threads.

I now think I can remove the corroded threaded insert and I will have a normal lever with the standard male threads on the end. This piece has acted as a threaded union for who knows how long on this boat.

That's odd. What brand is that throttle mechanism? What model and year is this on?

Looks like he has a Morse MV1, the shift handle has been painted black.

outerbanked wrote: Should this boat have the mv2 in it?

What year is the boat?

Mv1 with that housing through 87. They switched housings in 88 but the collar didn’t arrive until 89. Not sure if both are considered the mv2 (the internals are the same either way).