transf case or diferential ?

[The dream]

hey guys, when ever i put reverse con the truck i can hear a big "clank" metal sound from underneath the truck, kinda like a bell. A transmision guy (its an automatic) told me it might be the diferential and the diferential guy told me it can be the trans case. Any ideas? 

[VileZambonie]

Sounds like a bad u-joint to me.

[The dream]

Thanks Vile, ill check on that. Ill keep you guys posted.

[Irish_Alley]

x2 on the bad u joint if its not that maybe slop in the differential but the u joints i would bet on

[pjm257]

I have a similar problem but the clank noise only sounds off when i first start off in 4H. The transfer case and front axle were low on oil/gear oil so I changed and filled filled them both up with new. I replaced all the u joints except the 2 in the assembly that is infront of the transfer case as the hanes manual said I had to have a rebuild kit to properly replace them and I didn't have one at the time. It doesn't do it as much now that I changed the oil in the front end only under extream stress. The manual says there is nothing wrong with the transfer case unless it is making a noise in all gears and that is not the case.

So next week I'll be rebuilding that assebly infront of the transfer case to see if that will stop it. As it has 2 U-joints in it I am hoping that it cures the problem and I wont hear the clanking noise anymore.

[cracker0169]

Transmission mount will do that too.  Look underneath and have some put it in gear (brakes applied) and see if the assembly moves .

[Irish_Alley]

on my 94 it clinks only every once in a while its usually switching from r to d and its only 4x2

[Just-speed]

Put the truck in N and block the tires.  Now get under and check your U-joints while there is one the joints