I determined that they first screw on the bottom was 3 1/4 inches up from bottom of door opening. I pre-drilled all of those and then one at a time I installed the bottom screw and marked all the remaining holes on each one. I set the doors open with tape holding them open. I marked my pre-drill with a sharpie so I would not drill through the doors. I always select a pre-drill size by testing it on a scrap of wood to see if the screw strips or drives hard.
No man has a good enough memory to be a successful liar. Abraham Lincoln
2016 36FBTS Pinnacle
2016 F350, 6.7, 4x4, DRW, long bed
B & W Companion 5th wheel Hitch