Boating How-To’s - Replacing brass rear drain?

Hello, Got a 17' Sea Pro that has a 1/2" Garboard drain on the bottom rear of the boat. The 1/2" brass piece that screws in goes in a little crooked now. Guessing the threads on one or the other is getting stripped.

All of the rubber (twist or snap handle) ones I see are all 1" so I am guessing that I need to just replace the piece that has the 3 screws screwing it to the back of the boat. Can I just use some GE Type II or III 100% silicone on the new one, or do I have to use something like the 5200 Ive read about?
I have the GE already, and hate to have to buy a large tube of 5200 for the amount I need.

Thanks

I used 4200 on mine; had bought some 5200, but a lot of people had recommended against it due to the fact of how hard it is to remove if you ever need to. Clean it out GOOD, fix the screw holes if you need to, coat the inside of the drain hole with the goop, run a healthy bead around the shank and flange of the drain piece, and tighten it in...but not too tight as to squeeze out all the adhesive. Use your finger to fillet a bead around the flange/transom, let it sit for a day and you're done.

Thanks. I'll give the 4200 a try.