I haven't updated the decoder page to reflect the new database changes.. so the reason your J53S is comming up as "unknown" is because the latest it can currently crunch is 1952.

Hopefully by the end of the day, the cruncher will replace unknown when you enter that VIN with "3600 Commercial 3/4 ton truck (forward) with a 125.25 Wheel Base"

I will be slowly adding images to the VIN Cruncher.. so not only will you get the data for the VIN you entered, but it will also display a "Stock" photo of the truck as well.

an idea is only stupid if you think about it rationally.