Just bought my '97 F150 4.6 4X2 last month.
What is the easiest way to tell if I have limited slip or not

 

Ask the old owner? Hell Idk

 

jack up the rear so both wheels are off the ground..

put it in neutral..

turn the drivers side wheel by hand and watch the other wheel

if they turn the same way..limited slip
if they turn opposite of each other then no limited slip

...zap!

 

Easiest way..Get in the mud and see if both tires spin. That or read the tag on the diff. If it says something like 3L55 88 it's limited slip. If it has no L it is open. The tag should be attached to one of the bolts on the differential cover.
Alan

 

Or just post the axle code on your door jam sticker and we can tell ya all about your axle...

Adrianspeeder

 

When in doubt, take the easiest way possible. Here

 

Or, if you don't mind a little wear on the tires, just do a power stand with it. Put your foot on the brake while you press the gas pedal. If you leave 2 black marks - Limited Slip. If only 1 - not limited slip.

 

Thanks! This was truly the easiest way.

P.S. I do have limited slip

 

I know you found your answer already, but another way is to put one tire on pavement and the other off to the side in grass. If the tire on the pavement also spins, you have LS.