Hi,

I got one for ya guys.

I have a 99 chevy blazer with a 2 speed selectable transfer case.

I replaced the encoder motor about a year ago.

This weekend I was going 55 down the road with 4wd hi engaged and all of the sudden there was this thud/knock. It was similar to the thud when the front axle engages or disengages but it wasn't quite the same.

This thud/knock is not continuous and maybe happens every minute or so.

Any ideas or suggestions. I have the factory service manual but there isnt anything about this in there.