Yes Friend, as you suspected its the universal joints.
Just one uni. joint was worn out. Bought a new one for Rs.1300 and had it fitted to the shaft by an engineering shop.
Best part happened next, when it was given to the mechanic to fix it to the vehicle, he said its not done correctly by the shop.
The bugger at the lathe machine (was in a hurry to go home see the match ), had not centered the joint to the shaft!
Mechanic says there is about 2mm mis-align and would give a vibration at high speeds. if fitted like this. ( the problem I had was vibration at low speeds )
Then the time was 6PM and everything postpone to tomorrow. may be it will be needed to do everything from the start again as the uni-joint caps are steel welded to the propeller jaws to prevent it from coming out. This was done after boring the jaw to accommodate the new uni-joint using a seamer. The caps were fitted to the jaw using a hydrolic press machine.
I think this is pretty messed up now. I'm Thinking of buying the whole thing from a recondition spare part place and fitting it.
Hate travelling on bus and with the propeller shaft in hand its going to be a funny day tomorrow .
All this trouble because my father is sick these days . otherwise bugger would get these done for me as he did all these years , anyway time for me to learn the trade now
thanks all , will be staying around , there's lot to be learned from this forum and good people.
cheers