To my knowledge there are 3 generations of the rear shock. Gen1 on the '87-'00 bikes, Gen2 on '01-'16 and Gen3 on '17 & up. All are crap. If you are considering spending the kind of money they want on a new one, go for a quality after-market one. It makes a tremendous difference, especially if you do the front end suspension work too. I purchased a Works Performance shock. Works Performance went out of business when the guy died. I think his daughter re-opened under the name Worx Shocks (Worx Shocks) There is also the YSS option talked about here: https://www.tw200forum.com/forum/per...new-shock.html
If you don't want to spend that kind of money, then my advice is to purchase a used Gen2 from ebay for a reasonable price.