Another one i spent time on.
I couldn't find the right nylon spacers, the L shaped ones that are shown in some pictures on ultimarc's site so what I ended up doing was coutersinking #4 1&1/2" bolts/screws (bought from Home Depot) to an extra scrap piece of wood, using regular nylon spacers (available from most hardware stores, i couldn't get the right size from home depot, went to ace's hardware) and nylon washers to go between the ipac and the #4 nuts that came with the bolts.
then just used 1.25" screws to drill the extra piece of wood into the side of the cab... (from the inside of course)... prevented me from having to drill in from the outside, replug the hole, restain, etc...
hope this helps!