Looking seriously at a 1999 DSDP3884 Dutch star

I called the Cummings/Allison shop they told me the miles are so low I would be wasting my money. I drove it and wow, I am impressed. I found one thing that is troubling, they will have to fix it. The oil pressure gauge acts weird 42 them pegged then back to 45 then 90 them pegged again. Not slow swinging action but snap to the different locations. I think there is a short somewhere. No trouble codes . Nothing. It shifts great steering is perfect. I am impressed with this unit.