My 1995 pickup, five speed and 22re has a vibration when locked in 4WD high.
I just did new front axels,changed the front diff,front drive shaft.I only feel the vibation when its in 4wd High.In 4wd low I cant tell if there are any isues.

 

does it only happen when your on the gas? if so, U-joints maybe.

 

Did you match the gear ratios? Did you MAKE SURE they were the same, or did you just take someones word for it?

 

Something like that is happening on my 85, and I found it. I have the front driveshaft with the 3rd ujoint, but in the knuckle you have the rotating cup( I guess) with a bearing in it. Mine is wore out, but only vibrates in high 4wd. Too bad I cant find that bearing anywhere

 

The gears are matched.U joints seem fine.First we tried another drive shaft.Still had the problem.We drained the fluid we found hunks of broken gear, so the front diff was changed.We installed all new front wheel bearings and upgraded the hubs because they were squealing.Installed re man axels.
Jack it up everything spins with no effort.