1988 Dodge pickup, why do I do this stuff? Anyway got it two years ago it’s been a ‘work’ in progress to say the least. After replacing the fuel pump again got it running nice but no oil pressure (I knew this before) so I had a Ramcharger back 20 years ago the had no pressure found out it had baked sludge in the pickup after pulling pan. I thought this was same issue so off came the pan, no sludge but someone had been in there at some time before I got the truck. Changed oil pump and screen and checked bearings (new) still couldn’t figure why no pressure, maybe the pump? Anyway back together (a choir laying on the ground!) changed filter replaced oil, fired up still no pressure, light stays on. So on a whim I put a hard oil line and gauge, 65 pounds of pressure, the dang sender unit was the problem the whole time !!!! Funny how you get on one tract and can’t see the forest for the trees!. Anyway rant over just had to get it off my chest.

That's a familiar story that I think all of can relate to.
I'm just happy it was you this time instead of me!

Still, way better than the other way around.
Many years ago, about had a heart attack over a sudden oil-pressure light coming on.
Spade terminal had somehow come off and grounded.
So yeah, like Mike said, that kind of thing has bitten a few of us...

been there, done that, got the T shirt !
but was happy it was the sender [or connector, or wire] instead of bearing issue !

I got fooled years ago with the oil pressure sensor on a 1995 Magnum 5.9 V8.
I wanted to know the actual pressures at different needle positions on the stock dash gauge..
I left my sensor in place and bought a replacement oil sensor and rigged up an adapter with bleed off valve to connect to a tire valve expecting to create and then read from zero to 50 psi using air pressure from a tire.
The stock Dodge sensor “cuts off” suddenly at low pressures.
You might have 8 psi but the output will be zero.

Perhaps this was designed in prior to OBD-I computers to trigger a dash light.

I had the opposite problem with an 88 d100 and oil pressure.
I had to do a valve job on it, and found out that the original '302 (casting number) heads were cracked. This was a roller lifter engine, back then I didn't know that the '302s had fatter pushrod holes than earlier 318 heads. I had a set of older 318 heads here and figured "hey it's a 318, any 318 heads will interchange" but no. The sides of the pushrods were binding in the too small holes in the heads. (Probably '163 heads, which seem to be the most common ones I tend to get my hands on)

The roller lifters being taller changes the pushrod angle. I got it all back together and started it up and no oil pressure when I had fantastic oil pressure before I swapped heads.... I didn't understand why at the time, as I had done head swaps on 318s before that with no issues.
But this was my first roller motor I had ever been into. So I wound up paying $400 at a junkyard for another set of '302s (this was back around 1995) and those heads were hard to find back then. Plus the trip thru the machine shop to be sure these weren't also cracked.
I ended up doing a complete overhaul on that engine, before I was done. That was the most expensive 318 I ever had.
That doesn't take into account all the problems id had with the throttle body efi system on that truck. (1st year for that setup)
I'm just glad "that" system wasn't around long-- story for another time

I do same kind of things. I think I'm usually expecting to be the most difficult thing and NOT a simple fix, so I foolishly start with the more difficult fixes!

I will tell you one from the other side. My brother had a 96 1500 with a 5.9. He told me he would be going down the road and the oil pressure gauge would drop to zero. but no engine noise. So we put a sending unit in it and it still does the same. So we figure its the cluster. Installed a manual gauge, no oil pressure. We still laugh about it. Birdtracker