Newby here,

I'm looking for info regarding sudden loss of oil pressure in a '68 with a 289 2bbl/auto. There is oil in the engine. One stoplight it was ok next light slight ticking and 0 oil pressure.

I assume that I will need to drop the oil pan, crossmember, etc.

Anything special to know before I start?

RP46

 

your pickup could be clogged or the oil pump driveshaft could have broken.

 

Spun a main?

 

Or major cam bearing wear.

 

Aftermarket guage? Electrical or mechanical?
Take the filter off and cut it open...look for debris (metal, copper)
Report back....

 

Got it. Broken oil pump shaft, twisted up like a candy cane. Looks like the pump tolerances were a little loose and the pump jammed and twisted the shaft.
New pump, pan gasket set, 4 hours later, all done.