Welcome , if you have a Massey ferguson tractor dealership in your area, they should be able to find the part number and find out if it is available. I will check your number later today, I am in the middle of a blizzard right now and not sure if I can get out of the house. Noel
The serial list for the 10's are in our manuals section, but here is a snapshot of the numbers. Looks like a 70
As for the pulley part number, if you go to agcoparts.com sign in as a guest and type 10 into the search area you should be able to bring up a parts list. They had a few variants, so watch for serial number breakouts.
Replacement part for the pulley? That would be a tough one as the pitch is special on these machines. Also, it's a one piece pulley for the drive and attachments.