hi,

see the vacancies comes from psus is mostly for recruitment of electrical, civil, mechanical and ece stream, production is being a sub branch of mechanical, that why only production engineering recruitment is very less, I suggest you to apply for all the recruitment if you have valid gate score, mdl, ongc, iocl, generally hires production engineers,

if you are interested for m.tech,  You may use Careers360 college predictor tool to know your predictable colleges

https://engineering.careers360.com/gate-college-predictor