I found the genuine optional equipment list of my '79 Blazer. It has many optional equipment listet, among is a locking differential with code 1G80. I was told that GM offered two types of locking differential's. A limited slip differential and a 100% automatic locking differential (the M1009 CUCV where equipped with this 100% automatic locking diff.). Can anybody tell by the Code which locking type I have with my 12 Bolt rear diff?