John and Mike make good points. A "normal" unit marking would usually be a single line and larger letters about 4 inch tall. When I looked over the order of battle list I looked for units that had numbers that went with the 63rd Div.
I still hold out hope for 63rd Infantry Division.

The lower line does not look right for a date. I forgot that the truck had a van body until Goran added more photo's. SCR is Signal Corp Radio as in "SCR 300" etc. There were Artillery repair van like this and radio vans?? The vehicles are the general responsability of the Ordnance Corp. So take your pick.
So I could see this as a vehicle identification stencil in a depot. But not enough data for a shipment stencil.
Goran, any other information inside or outside the van body. Can you tell what equipment in contained?
Keep sanding - carefully
Cheers
Cat Man