treefarmer - Here is a helpful link list that's right here in this forum. Of those links, 3 Legacy Tech Tips (all located on this Legacy Tech Tip page) are most on-topic to your truck and will give some great info towards your bed assembly and installation:

Bed Mounts for AD Trucks

Build Truck Beds Sides and Front Panel

Rebuild Bed Wood

Generally, the vast majority of reproduction bed sides come predrilled for the fenders, like this one offered by Classic Parts.

If you search through the other posts in this forum, you will find lots of helpful info and links on your bed building info.

Here's a link to a Early Chevy Pickup Bed Restoration downloadable pdf created by Jim Carter many moons ago. I've not tried to download it, but it may be something you want to try.

There are lots of other sources in the posts and perhaps others will chime in and add pointers or links to some that will help you in your project. smile

~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)