if your uncle is in grade 19 and his salary is 75000 approx than this because of the reason that usually in OMG u get grade 19 in 8 years and with only 8 years service and increments this salary is good enough...
But as you are saying that your uncle is non CSS than he must have passed SOPE and if now he is in grade 19 than it depends on his previous service including the grade in which he was serving before passing SOPE. it can be anyone btwn 11-16....
so it all depends on no. of years in service.....