I have a 1992 Toyota pickup with 90,000 miles. It has always been taken care of. One day I noticed a knock, which was barely noticeable. You couldn't even hear it with the heater on but it progressively got worse. It ran to the point where it's louder than the engine in a matter of minutes but hasn't gotten any louder.
Since then, I've driven it less than 8 miles. I have been told by multiple people they think it's a rod knock but the knock will cut out for around a second at odd times, like when you come off the gas and push in the clutch.
I may be wrong, but wouldn't a rod knock be continuous? At the same pace, after we took it to a professional mechanic, (who did nothing after two weeks but listens and say they thought it could be rod knock) I picked it up and drove it 2 miles home. It's developed almost three other knocks, so I guess I could have spun other bearings.
I let it run for awhile. At first oil pressure was normal and then after about 10 minutes oil pressure dropped significantly. When I revved it, it would bring oil pressure back up but only for a little.