Are there bed differences between types and wheelbase?

[mjshealy]

Hello all. I just recently acquired my first 67-72. I have been coming to this forum for answers on a lot of things, thank you all for sharing knowledge and helping me learn. My new truck is a 1969 C30, no badges other than Bowie on hood and "Custom/30" badges on the fenders. I have gathered that it is a camper special, at the front of the bed it has that factory seam with 8" front bed extensions.
I just removed the longhorn/camper special bed, it is beyond repair. The extensions are in decent shape, so I cut them off at the seam and bought a regular long bed. My plan was to attach the extensions to the new bed front and put it on, but it appears to be different. My extensions are 8" long, where I read everyone else posting they're 6" long. Also, the new bed appears to have different bed supports that mount to the frame, as it is taller in the rear, and also the wheel openings are in a different spot.
On the old bed(without extensions) I have about 33" from the front of the bed to the bottom beginning of wheel opening, on the new bed I have 36".
The longbed appears to be a regular longbed with 6" extensions, so what is different? Am I just going to have to cut 3" off the front of the bedsides? And why are the bed rails/supports taller?