2000 blazer 4WD auto undercarriage roar. I have replaced:

- Wheel bearings

- shocks

- PV(or is that CV) rods

- Tranny overhaul with new bands(reverse shell broke)

Problem started with a clicking/grinding sound while driving after tranny was fixed, also has a roaring sound similar to a flat tire only while driving for awhile.

Placing the Vehicle in 4WD from 2WD stops these sounds.

NOTE: Wife said the 2WD kicked out while driving, and this was before the Tranny fix.

Q: Could this be an 2WD/4WD Actuator Problem?...what about the roaring sound?

All trouble codes are green across the board.

Thank you vary much for any responses.