86' CJ7 6cyl, NV3500, CV Style Shaft, 9" rear, 39.5 Swampers, 4.56 Gears. I recently replaced a T176 Tranny, b/c w/ my gears I could only go about 55 b/c my rpms were screaming. The new tranny is about 4.5a" longer so my rear is not perfectly lined up w/ the tranny. Usually, it should be just a little shy of a direct shot at the tranny to allow for movement under power to then align. Now when I get up to around 65 the sticks on my tranny and the motor and the whole truck is shaking. I thinking its probably the driveshaft being out of alignment w/ the rear & plan to cut the perches and set it up for the new tranny, but my question is do you think thats the problem? Or is there anything else it could be? Thanks for any and all help.

I would start by looking to them 40" tires! That is the most likely. Then look underneath.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

It seems to be either the driveshaft or something with the motor. We actually took my wheels and tires off and put them on my brothers bronco and did not experience any vibrations. Any thoughts?

I hope who ever put that 9" in there was smart enough to put that driver side
offset in it, If they didnt good look removing vibration, that offset in a cj is
to line everything up the engine is even offset 1 1/2" so front driveshaft is in line.

I put the 9" in Jeep. It was built by Currie & set up for a a CJ7 w/ a 4.5" suspension lift. The angle was perfect, but with longer tranny it is off a few degrees now. I figure this is the problem area, I was just wondering if it could be something else.

The pinion angle at trans output has to match rearend pinion angle on the
same plain unless you are running a cv shaft.

I'm running a cv style shaft. After putting in the trans it is off several degrees. Think this is the problem, just wondering if it may be something else. It's not terrible, just can be perfect so I am trying to narrow it down. If the driveshaft is not in alignment with the tranny (almost a straight shot to the back of the transfer case, little below to allow for torque under power) this can cause the vibration. Will it cause the motor and tranny to shake as well?

CV's must have the pinion pointed at the t-case. If it is not, the single joint compounds the amount it is off by. Repair the angles if it is causing the vib. or not.