D7G serial number question

The local Fire Dept. has a D7G dozer, serial # 4YB00010. I have a old serial number book but it stops at D7F and my Newer Cat book does not have a listing for a 4YB. What gives with this? I was told it was a 75 model but after finding the serial # plate it says 1982 and delivered in 11-1983. It is supposed to only have 400 hrs. on it. catskinner

4YB is a military serial range. 4YB1-up is equivalent of 92V11898-up.

I forgot to add to my post the second time that it listed it as a USMC tractor. Thank you for the info. catskinner