1954-1955st 235/261 valve cover (which could have been later used/placed on any 54-63 high-pressure 235/261).

Find and post here the casting codes.
In particular, the head & block date casting codes (but, also post the head/block casting codes).

I do not recall if you posted the Engine Serial Number (pressed into the block, rearwards of the distributor).

Nice truck.