[rekrap8]

Mine does the same thing in 2nd and 3rd (5spd). It sounds like chains or rocks gridnign almost.

 

[lmeyer9916]

Mine makes a rumbling/grinding noise when I idle around in 2nd or when I take off from a stop. Brother's truck does it as well, just clutch noise I guess? Makes me wonder what kind of shape the damper springs in the clutch disk are in...

OP, your noise is coming from the front of the truck?

 

[rekrap8]

Mine comes from the front. And it only happened when accelerating lightly under low rpm's in 2nd and 3rd

 

[svt2ctd]

nv5600? its normal..these trannys make a lot of noise.

 

[lmeyer9916]

Have you looked around up front? Look at the harmonic balancer to make sure the rubber hasn't deteriorated and the bolts are tight.