When I kick into pass gear or drop down a gear or two there is a vibration I can feel in the floorboard . Under normal driving conditions even towing a travel trailer its fine no vibration only when get on it . Looking for some guidance on this issue, 1994 f 150 xlt extended cab 302 v8..............

 

Ok so now new u joints all 3, new center bearing, new transmission mount ,and the drive shaft checked and balanced and still get this vibration help!!!!!!!!!

 

I was having the same issue after i had my trans rebuilt and found my trans was over filled. I pulled out a two litter of trans fluid and it is just now in the middle of the "do not add" sec of my dip stick. it was also dripping fluid in my drive way. I also ran my truck in drive while on blocks looking for something that would cause the vibrate issues and found one of my wheels to be wobbling up and down about a 1.4" so I also replaced my 1 1/2 spacers too at the same time allthoe this could have been my new tires I changed it anyway. Now I have no issues. I think it was to much fluid tho.

 

this vibration occurs at 3800 to 4300 rpm only. will stop at higher revs or on the lower side of 3800 ,no vibration occurs as long as your out of that rpm range. fluid is at correct level it was doing did this before fluid and filter change still puzzled.