If it's a HO, then it's at least an 01.
Find your vin#, then count left to right 10 digits. The tenth digit is the year model.
If it's a letter, not a number, then count backwards using the alphabet.
Your next question will probably be: "Where's the vin#?" LOL
They put them in several different places depending on model. Also, they're engraved on the metal frame (not a plate or tag) and can be very hard to see.
Look in these areas:
On the bottom frame tube on the left front. Kind of under the oil reservoir.
On the right front frame downtube under the right fender.
Under the seat.
On several models they were dumb enough to put a sticker right on top of the front plastic. Those usually didn't last too long.
They just got kinda crazy with where they put the numbers. On the 450, both the vin# and engine serial number are on the engine itself.
And yeah, on those models you've got the drain plug underneath and the dipstick on top. If you're changing the fluid, then it's one quart.