I feel a vibration I think it is comeing from under driver seat not sure it happens in 2nd gear at about 1/4 throttle and in third about 1/4 throttle when I floor it it is not there can it be a clogged cat or u joint any help is appretiated TY

 

If it's the cat, you'd have engine power problems. ????

With the vehicle jacked up and the truck in neutral at the trans. and t-case so the driveline and ouput shafts rotate freely, inspect the driveline. Look for grease in the u-joints...you may just need some. Look for cracked seals or caps in the uj's. Look for leaking fluid and excessive play at the t-case flanges.

Then again, maybe your seat is loose...

 

Well today I went and greased the drive shaft added oil in my rear diff as I greased the front shaft I noticed the shock bolt was loose so I tightened it up and it seems to be ok I also noticed it looks like my oil pan gasket is leaking a little bit Is it just a matter of draining oil then remove pan and put new gasket on and tighten up????

 

Yeah, a loose shock would produce vibrations. Congrats on the simple fix.

The leaky oil pan is a different story...if it's in fact leaking from the pan. If you're sure that's the location of the leak and want to fix it, you will have to drop the front differential down to get the oil pan off.