excess play in drivetrain

[superdutyscaler]

first my truck is not a 7.3 its a 5.4 but i cant get any help on fordtruckenthusiasts.com so i ask for your help now. I have a clunk sound when i first start from a stop and when my truck shifts. i installed brand new u joints about two months ago and i packed the rear slip joint full of a very good grease. still have it so yesterday i got under my truck again and i can push up on my transfer case and the tranny/transfer case moves up about a half inch? Is this normal to have that much play becauase i think thats my problem because i do feel the clunk under my seat so im leaning towards the mount?? Also if you grab the pinion gear output shaft on the rear axle r you suppose to be able to turn the shaft about a 1/16 to 1/8 turn back and forth?? Im going to take a video tonight to post the problem to help out

[superdutyscaler]

really? i understand i donthave a 7.3 but everythingother than themotor is the same. no one can shed somelight on this for me? all i need to know is if the tranny mount should move this much

[late_99_PSD]

That video would be very helpful, but from what your describing, yes that sounds abnormal

[superdutyscaler]

i checked my dads 2000 4x4 diesel, my brothers 2005 4x4 f-150 and are new 2010 E-350 van yesterday, i parked them on level ground pushed the e-brake on and left the transmissions in neutral. Went underneath of them and spun the driveshafts with my hand and all three have the same amount of slap back and forth as my truck does. So after that i think the tranny mount must be bad so i ordered a new one from the ford dealer for 45 bucks and ill install it tomorrow and post back

[Jonboywv12]

it might be the yoke going into the rear end it maybe just be worn out, as well as the u-joints on the rear end and maybe even the straps holding it in. i had the same problem and thats what mine was it make clunk noise just shook the whole truck.

[superdutyscaler]

bought a new transmission mount from the dealer and installed it, it almost completely got rid of the thud i was having from a start. I was at the local big truck repair shop picking up one of our fuel deliver trucks for its yearely inspection and was talking to the mechanic and he said that mobil1 grease is junk, especially for the slip joint on the driveshafts. So he gave me a ziplock bag full of this very thick heavy silver drivshaft grease that he uses on all the big rigs trucks they fix. so ill do that tomorrow