Hi Dan,
The first series of numbers on the drawing (3505102-3) were the assembly line issue part numbers. The second number 3505100 was the service order number. These numbers were "Purchase Order" numbers that became the actual part number for the part. The service order number could have been issued because a different vendor was used for the service order parts. Tom Barcroft (our newest employee at ECS) is a retired Exec for Chrysler and used to be involved with this part of the process. He explained the protocol for how this was done regarding these parts and their assigned numbers!