One option for managing different revisions is to create similar item numbers in your shopping cart to the original item, then add a (-R2, R3, etc. item to the store module so that these added items can be considered revisions. An item with revisions might have sister items that look like these:
Within the Parts selector module, you can then describe each of this items as revisions. This approach also allows you to have unique parts lists, .pdf manuals, etc. for the revisions so that parts can be purchased.
Please see the attached video for a more information: