8.75 Sure Grip Help

Pick up my pumpkin (741, 3.91 cone type) about two years ago and had it benched tested and set up at a qualified diff place. Yesterday did a "little" smokey up the driveway and noticed that there was only one strip from the pass side (sh*t). I jacked up the (drivers) side only, with brake off and in gear and couldn't rotate the tire (which in my mine is a good thing for posi type)??
Next I lefted both tires, out of gear and they turned in the same direction.
Should I be still happy? or could something still not be right here? I thought just maybe the cones have worn to a point that they don't grab with a load anymore. Any other test I could do?
Thanks, Jim

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