Bedside compatibility through the years???

[May70]

My previous understanding was 67-72 longbox fleetside bedsides are 'compatible' or 'the same' per say, however I know some have a metal floor and others have wood... I thought that wood and metal floors were just options and they were all 'interchangeable' to fit into the same beds.

I have a 1970 c20 with no trim, long box wood bed. My bed has the marker light and reflector at the back on both sides. My bed has rust through all over it and I know I need a donor or new one.

Today someone told me that the 70 long bed is different and that all years wouldn't fit. (what???) I was looking at bedsides someone is selling off a 1970, $600 for the pair. Will all/some/this set fit? Im not even sure what the going rate is for used bedsides but I was told re-manufactured is like 650 each shipped. The ones for sale were sandblasted and have surface rust, a couple rust through places around fender and a some dents (judging by pics). Are those bedsides something a new guy should take on or try to find better quality? I believe I will need every thing else including floor wood brackets/supports under it...

Info appreciated.