Joe, the placement for the back hole for the emblem is 20 and 1/2 inches from bottom of the fender and 4 inches from the rear of the fender at the door seam (drivers side).You will be able to locate the balance of the holes by the mounting studs on the emblems.
I had the fenders off the truck so I had no problem using the original pins on the emblems.I would not use adhesive or tape to mount them,they are heavy and I doubt they would stay.You can get to that area but it is a tight reach because of the air dam.
There are no gaskets behind the emblems on my trucks and I can't recall seeing a truck with gaskets.
I wanted to scan a page from the assembly manual for you but I was unable to do that.Good luck and if you need anything else just let me know.
Hobert
