I have recently purchased a 2013 Lariat straight off the lot with 10 miles on the odo. When checking things out and reading the data plate on the door and the window sticker this truck has a 3.55 open rear diff. confirmed by the door code of '19'. Now the question......and the confusion. I had thought the axle was an 8.8 with a ten bolt cover, but this one has a twelve bolt cover and looks (cover shape) like a 3.73 axle. Can anyone shed some light on this. The reason I ask is was I was checking the possibility of purchasing a TrueTrack for this truck as my last one had. In addition, there are absolutely no plates attached to the cover bolts anywhere for any additional info.

 

Think I tracked down my own answer. Looks like this is a 3.73 rear w/355 gears, if this is true, would this also have a 34 spline axle ??

 

Isn't a 12 bolt cover a 9.75" rear? That rear had several different ratios available.

Before you think about putting a locker in it, try it out, I hear that the traction control is very effective.

 

You can get the 8.8 and 9.75 in multiple ratios. The ratio itself has nothing to do with which rear size you got.

 

What a dumb a$$ I can be!!......I meant to say 9.75..guess that's what age does for you. Guess I have a 9.75" with 355 gears. Now if I can narrow down the spline number, I'll be all set......Thanks guys.

 

there should be a metal "tag" on one of the bolts that confirms the axle code. in your case it should say something like "355NLS"

 

Pat..there isn't a tag to be found anywhere on the cover. That one thing that makes this puzzling.