NP 205 transfer case help

[79camperspecial]

ok i just went through a long process of switching over from a NP203 to a NP205 transfer case in my 1979 F250.now i got one hell of a noise!!!! everything runs ok goin 40 down the road until i hit a bump or let off the gas coming up a hill witch jars the truck. it sounds like a rapping or tapping kinda noise, not really a grinding, coming from right under my seat and just got me so confused and lost. its hard to believe its a bad transfer case. i've posted before on here with no luck of any replies and just asking for someone to please finally come to my rescue. any advise at all will be greatly appreciated. i'm on my last thread with this truck.

 

[farmeruss]

look at the front drive shaft angles they may be to tight and the u-jiont is binding up how did you mate it up is it a auto trans or manual one dose it have a skedplate onit is it stock hight or is it higher this can change things to