from what i read...the 39 is a "serial" unique number assigned for identification which varies...if there is not a serial number on the anvil than it could be a factory reject.
100 lbs...and u can tell by the 10 on the anvil 10=100, 20=200 and so on..at least that's what i read when i read up on the anvil, but i could be wrong. i placed it on a scale and it read 107lbs.