measure the height of the "H" in husaberg, then measure the height of the case as shown. a 650 will be 3.2 times the size of the "H". other models won't be close. see pic
i'm guessing you don't trust the p.o.
I have been going through Husaberg engine numbers, yours is a 380. 2002 by the looks of you numbers. Engine size first 3 numbers the 4th numerous will be year they the last 3 numbers is the build number