If the tool has the same model number, it will be the same tool regardless. There would be no way for a service center to know what part's to order, or replace if DEWALT sold a lower quality DCD985 in a combo, and a higher quality DCD985 sold as a single. A DCD985 will be a DCD985 no matter how it is purchased.
Over the life of the tool, small tweak's are changed here and there. They are given a TYPE number. Type 1, 2, 3 etc... That would be the only difference. These are progressive changes that roll-out over time.
Thanks for the help!