broke down need a shop

[Sasquatch]

while pulling a hill with a 40,000 load, it made an unusual squeal, and started loosing oil pressure, as I eased up and got up the hill to the off ramp the oil pressure was down to about 20psi, and was knocking, but boost pressure, coolant temp, and exhaust temp were all good. I limped it to the fuel stop on that exit, and shut it off. Checked oil and it wouldn't even touch the dip stick, it was about 3 gallons low by that time. ( I found that out later when towed to shop and we checked the level by adding oil.) but when I tried to turn over engine while still hit, it was very labored and would not hardly even turn. After cooking over night it did start up, after the mechanic made sure the turbo had not filled the air charger with oil. But at this point we haven't opened it the rest of the way. But it is knocking really bad, and the engine has no oil pressure even though there is oil now.,