when letting out the clutch while at a stand still i can feel something grab and make a thud noise in the rear end ive been told that it may be my splines on my drive shaft need greased but i ve done that and it still hasnt subsided my dad says its normal for the rear end to have slack in it to make it do that but i say that there is too much slack in the rear end what should i do?

 

did you check your ujoints before you greased everything?

 

sounds like a u-joint thats going bad - thudding is the general cause of that when braking and/or starting from a stop.

 

could be the slip yoke

 

I had the same problem and it was the slip yoke. Take the drive shaft out and lube it up with synthetic grease