I was on my way to work and only got about a half block from my driveway and CLUNK when my Blazer tried to shift into 2nd gear....but lost forward motion instead. Reverse still functions, as do 1st and Park. The clunk was so intense, I thought it felt like the front drive shaft had dropped from the front end, and caught the street then banged up against the under-side. Tried a slow test drive in the parking lot across the street later. Same symptom. Fluid checks out normal. On another thread here, I read something about a VSS on the top/rear/driver-side of the transfer-case as a likely fix. However, I haven't seen anyone else with the same exact issue as mine. I guess there's another reason I named it MONSTERDAD when I bought it.

 

Broken "drive shell"? Sounds like rebuild time.

 

Yep, overhaul time.