well I think I found the transfer case shift relay module. Little black box about 2x2.

This is the number written on it. I tried finding it on the parts on that site you posted and also on google but come up with nothing.

F75B-14B194-BB

When I select 4L i can feel it clicking inside the module relay, but when selecting 4H nothing, just the relay in the RPO box clicks clicks clicks.

Thoughts?

Any way I can check if the relay module is working correctly? Bench testing it or something? There are a lot of pins on that module realy.