I can't say for sure, but I doubt you're going to have many choices in the rear bed department. Not likely that any manufacturer is going to make one with and one without holes. Like much of the other parts, you're likely going to get one that has all the potential options to fit all years and all models, and just lets you deal with any "extras" on your own, if you're doing a religious restoration or custom where some particular feature is not desired.
In some cases, the different vendors might have different versions of a body panel made for themselves, either to get a better price, a better quality product, better delivery times, more options, or all of the above. I know we do on the more popular parts, such as front floor panels.
But for the rear pan, there's probably only one or two manufacturers producing them.
Like I said though, I could be mistaken on that score. But it sounded true at the time. ;D
Paul