On my 04 lariat 4x4 the axle code is 26, which from my research says 3.73 non limited slip. Which a 4x4 with non LS is a sad thing. But when I spin the tires they both spin. As if it IS limited slip. So maybe the chart I found was wrong? If I'm right an open axle should only do one-wheel-peels correct?

 

26 is a 3.73 non limit slip

 

1959 thru today: If the AXLE code stamped on the Rating/Warranty Plate (1957/79), printed on the Certification Label (1981 thru today) begins with a letter: Limited Slip. If with a number, no Limited Slip

 

With both rear wheels off the ground, trans in Neutral and parking brake off, turn one wheel. The other wheel will turn in the opposite direction. With limited-slip, they both will turn in the same direction. Of course, a quick test is to simply spin the wheel on some gravel where you can see the evidence of spinning - one wheel will spin. With limited slip, both wheels will spin and it is usually harder to spin them than it is the one.

 

When I do a burn out both wheels spin and it begins to walk sideways, like a posi or LS would do. If it was a non LS it would only be spinning one wheel correct? So is it safe to say it's been changed?

 

I would not assume it has an LS unit... Both wheels CAN drive on a non LS unit if conditions are right.. raise one wheel, put trans in neutral and try to rotate the tire as mentioned above.