Oil pressure sending unit gone bad?

[cam.man67]

For background: I took the bottom of the Olds 350 apart a few months back to replace the oil pump, timing chain and gear, and oil pan gasket (along with new engine mounts). Pressure was great up untilabout 2 weeks when, according to the dash oil pressure gauge, idle psi dropped to 1 and 3000rpm netted me about 3.

Now, I know, of course, that that is incorrect since there's no valvetrain noise at all, nor am I having any temp or lubrication problems. That being said, I figure the oil pressure sending unit is faulty.

If so, what part number do I need? Half of the ones on Rockauto say they're for vehicles with a 60psi gauge, but if you look at the product detail, they're actually for warning light vehicles. What gives?