Vintage Dirt Bike Q & A

I recently bought a 73 or 74 CR250M and am trying to find out exactly which year it is.. Can someone help me figure this out? I know it's one of the two, but would like to find out how to tell for sure.
Thanks!

I have heard that frame and engine numbers that start with a 100 or 101 number are 73. Frames and engines that start with a 102 are 74s. I have noticed most original 73 models have early parts like castle nuts on the front motor mounts where the later ones do not. Maybe someone out there knows more.

I have this from this bb months ago.

73 and 84 numbers were as follows:
Frame 1000216 to 1025537
Engine 1000225 to 10228676
73's had the 1000 #'s.
74's had the 1001... and 1002... #'s.
Early cases broke and replacement cases had no numbers.

Hope this helps.