To all and especially Snowmobile.

You mentioned in your answer in my earlier post conerning a vibration in my drive shaft after changing all u-joints, bearing and pinion seal, that I should have preloaded the pinion.

I have never done this before...what I did was to use a puller to take off the flange, pulled out the old seal, put in new (tapped in with wooden block behind reversed flange) seal. I then torqued the nut on the flange to draw it down on the splined shaft. Final torque was at 160 lbs, would this preload the pinion?

I am going to follow your advice S'mobile, I have a lift in an enclosed building
to use. Do you think I should replace the tranny mount? I have jacked the tranny up a couple times with the present mount, though it looks very good yet.
Do you think I should open the rubber donut again and make sure it is set so the driveshaft is level as it goes through it? Check it with a level too. No balance plates have come off this shaft. Do you really feel the backwards bolt by the zirt could have a bearing? I could also re-torque to spec. all the flange bolts, is that critical?

The pinion is probably OK. If you can spin the pinion shaft slightly and feel the drag and it is just noticeable, all is well. If the shaft spins with a lot of drag (more than two fingers will overcome) then it is too tight.
The driveshafts have only two positions where they are phased correctly, not four at 90 degrees as many assume. The yoke at the front of the front shaft must be in phase with the yoke on the slip joint shaft on the rear assembly. It is the forging welded onto the shaft that you look at, not the one on the flange. Align the yoke on the splined shaft with it. If you study the rear shaft between its two u-j's you will see.
If that doesn't fix it then the shop that installed the u-j's bent either one of the shafts, or the yokes, while pressing or hammering in the new u-j's.