slight hollow knocking sound in great detail description

[pbilt]

i have a 85 2.3 it has a slight hollow knocking sound constantly that fallows the rpms its louder on the bottom and it sounds like its coming from the back drivers side it is louder when its cold but is still noticeable warm and its more noticeable in the cab then outside. the knock is louder at low rpm and gets drowned out a little bit at 3000 but is still slightly there the oil pressure is 60psi cold and 50psi warm after a long highway trip the oil is at 40 my temps never get above 185 with the heater on cold but on warm it drops to 160 any help is appreciated

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when im on the highway oil is at 50 but when i slow down its at 40 but never drops below that