Jerod,
A few clarifications, additions, and corrections to the material given/quoted by GMONIZ above:
"1947-1954 Advanced Design Pickups"
"Advanced Design Era"
I think the name is "Advance Design" series trucks for light, medium, and heavy duty Chevrolet trucks from 1947 second series (1947.5 or 1947-2nd) through 1955 first series (1955.5 or 1955-1st).
The analogous GMC truck series was called "New Design". There were many differences between the Chevrolet and GMC trucks during those years, especially with regards to engines, front sheet metal, gauges, and electrical systems.
". . in 1948 the four-speed transmission's gear shift lever was moved to the steering column from the floor..."
I think this refers to the three-speed transmission's shift lever moving from the floor to the steering column.
The 216 engine was used from 1947.5 to 1953 in Advance Design trucks (introduced in 1937) and it is usually characterized by it low-pressure oil system. The 235 engine was introduced in 1941 and it had a low pressure oil system in trucks until 1954. This older 235 truck engine was available as an option or standard in heavier duty trucks, depending on the size.
From 1954 through 1962, the 235 higher pressure oil system engine was the standard engine in light trucks; during these same years, a 261 truck engine was available as an option or standard in heavier duty trucks, depending on the size.
A 235 automobile engine (often called the Blue Flame Six) became available in 1953 on PowerGlide (automatic) Chevrolet automobiles. This 235 was the standard automobile engine from 1954 to 1962. It had the higher pressure oil system and hydraulic lifters (all truck 235/261 engines had mechanical lifters.
It is fairly straight forward to get any 216/235/261 engine to interchange. Some of the differences (that are easy to adapt or adjust for) were motor mounts and water pumps.
The GMC engines during those years (228/248/270/302) were longer and a little harder to adapt for installation in Advance Design Chevrolet trucks.
The GMC electrical system had a positive ground until 1955.5 (I think), while the Chevrolet system always had a negative ground. Both Chevrolet and GMC trucks had 6 volt electrical systems until 1955.5. A very common conversion is to change the 6 volt sytem to a 12 volt system (there is a technical article on this in the "Tech Tips" section of this web site.
As GMONIZ says above, read the Tech Tips, search this Discussion Board, and ask questions (and post pictures).
Good luck,
Tim
