as soon as i let my clutch out and giive the car gas there is a knock sound and u can feel it in the floor boardalso when i let off the gas u can feel it again. but its not a constant knocking. it just doues it each time u get on or of the gas and the car flexes.

 

Sounds like maybe a bad U joint. I would check them first and then move to the rear from there.

 

exhausthitting the floor?

 

it also does it when the car decellerate

 

Possible that the trans cross member has
rusted out or is loose. The torque on the
trans causes it to move in the mount.

 

well i just got rear ended when it started hapening

 

You need to get some lift time.
Look at the exhaust pipes and see
where they have moved too close to the
body or drive shaft.

 

found out waht it was my transmission mount was loose my rear sway bar and one of my control arms were also loose. but all is well now

 

Could have broken a motor mount