My High Low selector has seized up but I don't know where the linkage is to spray some penetrating oil on it. What is the easiest way to spray this?

 

Did you try to change into low whilst stationary as you need to be moving very slowly I believe about 5mph, check out the plate behind the gearshift. Tip: to ensure the low range changer works when needed regularly (once a month) change into low range for a few miles.

 

I have not tried it while moving nor have I ever had it in low since I have had it. The plate says 0-5 mph but I will give that a try.

 

I tried shifting it while rolling but same thing, it won't move. I don't want to push it too hard because I don't want to break it.

 

Crawl under from the passenger side front door. Look up where the front drive shaft meets the transfer case above the transmission you see it. If you have a second person inside the truck wiggling the shifter it will be easier to spot. Took me 4 tries over a few days with PB Blaster to get it loose.