97 Suburban 4WD driveline issues

[Keith Seymore]

Sounds like I’ve killed something in the driveline of the Surburban.

I’m getting a “brrrrrrrrrrrrr” on hard launches, sounds like a fan hitting a shroud except more metallic. May be coming from under my feet.

Does not do it on soft launches. Does not do it in reverse. Does not do it in 4wd.

Also had a couple occasions where, in reverse, it’s like it “pops” out of gear with a single metallic bang and then the driveline “freewheels” (ie, you can hear the trans/tcase spinning even though the vehicle is stopped. Only way to stop the driveline is to put it in Park and let the pawl catch it).

No obvious outside damage: rear shaft, front shaft, everything on the outside of the trans looks ok visually.

Trying to decide if it’s converter, transmission or tcase. T case controls? Any thoughts?

K