Just a quick heads up before you tackle the horrible job of the sending unit. I had this same issue on my 98 ram with the 5.9 V8. whenever I turned right going over 10 mph the gauge would drop to 0, then hop back up to just under 40. After ordering a new oil pump, rod bearings ( might as well while the pans down) and sending unit, I noticed the intake pcv vacuum hose port was wet with oil. So I pulled the hose out, and when I pulled the pcv valve I noticed it was dirty and sticking shut when blown into. This was a new pcv valve, only a few months old. So I cleaned it and the hose out thoroughly, didn't even mess with the oil sending unit, plugged everything back in, did an oil change and noticed I was 2-3 quarts low (the gauge was accurate, I was low on oil when it turned and the oil went away from the pickup tube). After that, started it up. Oil pressure was back above 40 and when driving it stays between about 35-50. Problem solved.