Low oil presure. Check engine light intermintantly on ,off. Cruise controll won't stay engaged. Any Ideas ?

The oil pump develops 38+ PSI? Did you attach a gauge before installing the new sending unit?
Cruise control could be a bad fuse, vacuum leak, or a computer/speed sensor issue.

No. I didn't attatch an oil presure gauge before installing the new sendig unit. ( I don't have one.) I was referring to the fuel pressure with the 38+. I've also found 4 leaks in the vacuum system. One at the "tomato can" red line , one at the heater control, white line. And to the top left of engine there are 2 presure control moduals with pink and yellow lines. These were also cracked. I used shrink tubing for tempory repair, I'm looking for a vacuum harness. I will probally have to start from line to line though. I checked all fuses and connections. I only have a basic eletrical gauge to check codes, slow going. Where is the speed sensor? And how do I check it and the computer?

For a carbureted engine, that's borderline. For an injected engine, it's really low. Most likely it's the fuel pump.

Many parts stores like Pep Boys and Autozone have loaner tools. Some of them have oil pressure gauges you can borrow or rent for dirt cheap. If you suspect low oil pressure, you need to see what the pump is producing. You're looking for a minimum of 30 PSI at idle, going to about 40-50 for regular pumps and as much as 65 for high pressure pumps.

You might try checking self-serve junkyards to find the vacuum lines you need if you want to keep it all original looking. Otherwise, Pep Boys or Autozone like stores again.

does it run OK? is this a continuation of another post?