oil pressure disappeared.

This is also NOT true of the more modern "trumpet" pickups used in Dakota/ Rams and I've had trouble with one and seen other tear-downs all full of sludge. There was a thread on here somewhere..........
Yes, they are flat on the bottom. The 4.7 engines also have a factory flaw where the pickup tube is actually too small and causes the oil to over heat and cook causing sludge buildup. Talked to a Jasper engine rep years ago about that and he said all their 4.7s come with an improved larger pickup tube.