Sorry about being pedantic, but Chevrolet referred-to and had documents describing 1955-1st series and 1955-2nd series Advance-Design or Task Force trucks.

1946 trucks were sold by dealers into 1947 until they ran out, but Chevrolet did not refer to 1947 first series and 1947 second series. The Advance-Design series of trucks is the 1947 series of trucks.

Does anyone have a Chevrolet document that refers to a 1947 first series truck?

Nonetheless, the above info is off topic.

Ryan posted: "the cab is '48 first series 1/2 ton"

As Alvin posted, there was only one 1948 series of Chevrolet trucks. But, maybe Ryan is referring to changes that might have occurred in the 1948 calendar/model year?

Nonetheless, the measurements Ryans is asking for could be measured on just about any 1/2-1 ton A-D truck (I think)?