Originally posted by 46 In Progress:
Is there any way to tell between a 54 and 55 1st?
You don't say if this is a Chevy or a GMC.
If it's a Chevy the 2nd and 3rd characters in the serial number are the only sure way to tell. Any of the other identifying marks are clues, but represent things that could have been changed.
If its a GMC it's even harder. The serial number won't tell you if the truck was manufactured as a '54 or '55 1st because GMC did not make a model year change even though changes such as the open driveline were made.
I've seen a list of production line counts by plant that say when the change to open driveline occured, and that's probably the best indication of which a given GMC really is.
You also haven't told us if the truck is a 1/2- 3/4- or 1-ton. My '49 1-ton is open drive and I believe all AD 1-tons are open drive. 3/4-ton trucks have a different arrangement. All the torque-tube vs. open driveline stuff above assumes you are dealing with a 1/2-ton.