I believe all rear fenders are the same from '47 thru '53, and the beds were generally the same (with the only difference being the hole for the under-bed tank on the early trucks.

On my '51 3100, there are 8 bolts thru the fender and bedside: two below the floor, two thru the floor angle and 4 more above the floor.

I have a diagram in my shop for hole locations in the bedsides, as I needed to patch most of them and needed to know where to redrill the holes. If you want that, I can share it with you.
Might be a little hard to read. The datum point for the measurements is the front of the rear stake pocket and the lower edge of the bedside (except as noted below) .
Hole #1 -- 4" forward and 1" above
Hole #2 -- 4-7/8 forward and 5-5/16 above
Hole #3 -- 13-1/4 forward and 12-5/8 above
Hole #4 -- 24-1/2 forward and 13-7/8 above
Hole #5 -- 35 forward and 11-3/8 above the lower edge of the open area over the axle (not the lower edge of the bedside)
Hole #6 -- 47-5/16 forward and 13-5/8 above
Hole #7 -- 54-3/4 forward and 5-5/16 above
Hole #8 -- 56 forward and 1 above

Note that holes 2 and 7 are thru the angle strip

Hope that helps out.
Attachments
Bedside Fender hole diagram.jpg (65.44 KB, 139 downloads)

Last edited by klhansen; 04/17/2018 3:51 AM.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.