I assume you are using 2x4 to go across the cab, to attached the monitor with 6 bolts (3 top, 3 bottom). I used "L" brackets (literally look like an L) to attach my 2x4's, for D9200 mounting. 2 to each side, on on top, one on bottom of the 2x4. But, I wouldn't rely on just 2 2x4's, I also built a shelf that most of the weight of the monitor rests on.