05 cummins 04 build date advise

[Robkiller]

So the truck was converted about 10 years ago to an RV. It had a custom 17k bed put on with a non commercial fifth wheel hitch. The owner passed but from what i can find from the shop that did some work for him and his friend selling it for his widowed wife it was his baby. He did everything it needed before it needed it. Take that for what its worth. I will be using it for the same to haul a fifth wheel travel trailer toy hauler around the US. I am giving him 23k for it.

The trans is an alison auto
I hear old trucks suck new trucks suck man leaves no options. I thought keeping away from def and piss in my engine was better so i went older. Maybe that was not smart.