Great info, thanks for the manufactures pics. A little small to read but I'll dig around on google later, working night shift sucks. Hopefully it's just at the front so it's an easy measure and cut, might even pull both cabs and boxes to get a side by side comparison and measurements next week when I'm back home.
And yes to be clear my truck is a '55 Second Series
Second pic (black/red) is my '59. I have the complete truck, this was after I took it off a '91 4x4 chassis and swapped it back to its original chassis, takeing off the front clip and digging deeper is when I found all the car cancer.