Is this usage correct? “versions N and prior”

Solution 1:

I think either usage would be correct, but I would lean towards "versions" for clarity.

Another example is this:

Suppose you had four boxes, marked A, B, C and D. Two of the boxes contain prizes, the other two are empty. You might say

boxes A and B both contain a prize

or

boxes C and D are empty

In each case you are referring to a group of boxes, so you would use the plural form of box.

You could read

Version X and prior

as

Version X and prior [versions]

The word versions is implied in this case. This may be idiomatic rather than strictly grammatical, but I think the reader would understand.

Regarding the colon, it wouldn't be correct to use it within a sentence, but would be fine in a list.