hey guys i've got a 91 s10 blazer 4x4. I get extreme vibrations driving at any speeds above 10-15 mph. I do not think it is bearings or anything like that, I believe my 4wd drive is stuck on. There is no 2wd light showing anymore and the t case shifter feels like it has not fully engaged in 2wd. Is there anyway I can manually shift the t case back into 2wd to see if it is my problem? Thank you.

Also, the steering is unaffected, and apart from the vibrations, still drives just fine. It just feels like I'm in a tractor trailer above 10-15 mph