Cadillac 425 final drive

Question,What type of oil would go into the differential of a78' Eldorado?. Also where is the fill/drain plug located? And what type of fluid would I use for power steering pump as this car has the hydro boost brakeing system.Thank's...Diesel1962

Regular 80/90 diff oil for the front drive and dedicated p/s fluid for the p/s system, flush out any old fluid in both units.

Thank's again Max.Was not sure about the differential oil,as my Toyota differential takes auto tranny fluid.Regular p/s fluid would work ok then?Was not sure about that ether.As it has the hydro boost. Never had a car with that system.Have a good day!!.Diesel1962...........