Think my truck with 177000 miles oil pump is gone.How can you be sure what it is

NO! as soon as you saw the oil pressure gauge NOT WORKING the first time and sounding like a diesel and valves clicking,you should have pulled over right THEN and turned it off.you could have rented/bought a manual oil pressure test gauge or had it tested.

Sounds like you may want to get it towed to a shop for diagnosis. It's not an oil pump gauge, it's an oil pressure gauge. Either there's a problem with the sender, or you actually have low oil pressure, which is bad. Check the oil level, low oil can cause all sorts of running issues, and eventually damage if it's not taken care of. If the oil pressure light (the red oil can) is on while the car is running, stop driving it and get it looked at!