I have done 4 of them now.  My process has been having the May-Wes catalog and tape measure handy to get right model.  Then just a good cleaning of plate and truck.  I have learned to clamp the poly onto the plate and try to visualize where all the holes go before drilling.  On one plate installation I saw that if I had moved poly just an 1/8" it would have been a lot easier drilling - and plate would have worked fine also.  I think that was the same plate that did not have mu clearance so ended up lifting it up to be able to get my hand under part of it to attach nuts to the bolts. I just have a regular drill and did not have any problems.  Those fancy magnetic drills would have made the job very easy.

I used to use those poly washers but like these better.  I see no problems with the clearance or any interference on any of my trucks or trailers.

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IMG_3989b.jpg (50KB - 63 downloads)

IMG_2622b.jpg (62KB - 51 downloads)