Oil leakage problem is solved. It was just the reverse switch under transmission. Now Mechanically all car is fine from below.
Mechanic put a very thick gear oil in it, he was saying something like CL. It was so thick that 2L of it took 5 minutes go down the funnel. I overlook it at the moment as i was concerned about leakage.
After some googling and youtubing, i compared Its viscosity to be like SAE460W or 680W.
Edited; Today i found, it was this oil, SAE 140/99 they call it CL
Is it fine for these old cars ?
Edited; Today I noticed significant clutch drag with this heavy oil. When it was in neutral, i pressed clutch all the way and start the engine, upon releasing clutch car was trying to drag forward and engine was getting load, rpm were dropping. Again on pressing clutch rpm were increasing while it was still in neutral. Should i change transmission oil to lower viscosity like 140w ?