Iron,
The trigger and the lever still make it a mid-80's or so action.The newer lever and the trigger w/push-button safety came around '88. Sheer speculation on my part is that it's a custom serial number that the customer asked for when he ordered the gun. As long as the number was unique Dean would do that. If the 4th character is numeric I would say it was something significant to the owner. If its alpha, the the owner may have had another action with that same number, as I do. Cyle can probably help you there too.
The stock can be refitted easily- maybe Cyle is doing some work-ask him. If not, Earl Hines in Cody Wy. is an excellent man to work on it.
If you want to read about the action, get ahold of the following-
ASSRA News, Mar/Apr '86
ASSRA News, Nov/Dec '91
RIFLE Magazine, #145, Jan/Feb '93
and , of course, the de Haas books.
I missed the auction listing, do you know who's barrel it is?
You might also run the name past Russ Weber, the gentleman who made the breechseater. He's a great guy and will help you if he can.
Good shooting.