Where to find tranny ID Code?

I think my tranny needs a rebuild or a repladement:banghead: . I lost OD and the car would run at 3500rpm at 120km/h (or 75mph), plus the tranny gives off this whining/grinding noise that sounds like an aircraft engine. no check engine light or any other lights whatsoever, no code came up on my OBD-II reader. Tranny has correct fluid level and correct fluid smell. The car is a 2000 GLS with 190,000km (119k miles) on the odometer. The tranny started to have this infamous intermitant harsh up-shift problem during local driving since about 60k miles ago, sometimes with the whining noise, other times without. The car started doing this harsh up-shift again when I got stuck on a congested highway stop-n-go for 2 hours last weekend, right before I found the OD quit working when the traffic started easing up. So I think they may be somehow related, especially if a whining noise accomanies the harsh up-shifts.

I have read about an inferior PC solenoid in the tranny causing the computer to decide to run the hydraulic at its top pressure, hence harsh up-shifts, to avoid otherwise possible damages to the friction parts, and I've read people saying therefore this harsh shifts is not damaging, just annoying. Not being against that opinion, I say bite the bullet and get it fixed.

Now questions for gurus here, I looked up car-part dot come just to see what they have for a used tranny, looks like our trannies are not compatible year to year, is that correct? I understand my car has a 3.29 final drive and that's what pro code FR9 is about, how about ID code either YCB or YHB? and these ID codes appear only come with 2000 tranny, but not with 2001, 2002 model years. Am I understanding right that I can't put a 2001 or a 2002 tranny on my 2000, neither can I put a 2000 YHB tranny in place of a 2000 YCB tranny? How can I tell what ID code my tranny has?

Sorry for the long post.
Thanks!