The rear door stops were different on 3105 & 3805 Panel Trucks compared to 3106 (rear panel-door) Suburbans.

1947-1955 Panel Truck rear door stop. It has a half-way stop and a full open stop (perhaps to allow backing up to a loading dock, etc).

1950-1955 Suburban rear panel-door stop. It stops at one position. (During Advance-Design years, rear panel-doors became available in 1950).

Tim