Looking to upgrade the interior to LED. Have got most except the overhead map lights. Have ordered two different ones which LOOK like they are correct but don’t light up. Anyone have some ideas? Many thanks!!

The only lamp in the interior lighting which is driven differently from the others is the main dome light, the spots and other interior lamps are all on a common Battery Saver output from the SEC with grounds through the individual switches. The main dome has the same power but is grounded by PWM from the SEC. So if it's the dome that's giving you problems, it may be that the LED's don't like the PWM signal. See EL-130 here:
https://www.nicoclub.com/service-manual ... 0%2FEL.pdf

Virtually all automotive LED's are not bridged and only work in one polarity. Sockets designed for bulbs are never polarized. So if it's a polarity issue and the socket isn't reversible, you'll probably need to open the fixture and reverse the wires.