need some help figuring out noise coming from differnetial
 

Help me need any and all information regarding this knocking noise in the transmission see when i go from park to drive the noise starts and once on neutral its stops but shifting back to drive starts up again with no gas although giving it gas does cause the sound as well. reverse no problem (sound). grand Cherokee jeep 4x4

That's coming from the transfer case. The front driveshaft yoke should not be spinning. JMHO, but it looks like a NP 249 with a bad viscous clutch that someone fixed by removing the front shaft and now it's totally snarfed.