Differential tag; am I reading it wrong?
 

Hey guys so I'm doing a gear swap on my rear end and I wanted to know what sort of differential is already on it so I looked up the tag online but it's not making sense.

The car is a 92 mustang, but I know a lot is not original. I tested the gear before I took it out and I know it is a 3.27.

Tag: 3L27 88 9K04

According to the decoder:
3.27
Traction Lock
8.8
1979

But I read in a book that Traction Lock was first an option on the 1981 car, and that the 8.8 wasn't even put in mustangs until 1986.

Whaaat? Can anyone help?

This is what I used: http://www.foureyedpride.com/joom/in...d=24&Itemid=40

9 also corresponds with 1989. They didn't use letters to distinguish between decades on axle codes.