I can't remember why I did, but I changed out mine from under the truck.

 

I tried that direction, but, it was just too uncomfortable... but then, working with my arms above my head has become somewhat problematic for me in any event..... Probably just me.

 

I drove for about 30ish miles total and I cut the truck off twice in that 30 miles to go into a store. I haven't felt the misfire yet so I might not need to change the crank sensor.
When I was changing the wires I left the snap part on the spark plug for the #7 cylinder so maybe it was screwed up by the heat of the headers and barely making contact. I got the wires for free too because of the warranty.