Series Id
In order to find correct vacuum hose diagram to the truck being worked on, the SERIES ID of the chassis must first be identified. To do this, locate the sixth digit in the VIN Number and follow the list below.
If the sixth digit is 1 then the truck has a 1/2 ton chassis.
If the sixth digit is 2 then the truck has a 3/4 ton chassis.
If the sixth digit is 3 then the truck has a 1 ton chassis.