I have a 2002 Tahoe 4wd with 122k. I drive it on the beach regularly and have recently had issues that the steering wheel pulls hard to the left when driving on the sand while in 4wd. It doesn't do this on (straight) pavement (I don't want to test turning on hard pavement in 4wd). All four tires are the exact same brand, model, size, condition and tire pressure. I have jacked the front end up and tested that both wheels are engaging/disengaging when the 4wd system is turned on/off. No unusual noise/sounds. CV (boots) all appear good. Any thoughts or suggestion on what might be the cause? Thanks in advance.