Yes, we see that alot with many brands. Distributor changes and vendor changes often go along with new packaging graphics and what I call series names. For the maker, who may be Pioneer (or even another manufacturer in China usually ) this more generic packaging allows the item to be sold in many different commercial outlets. And a catalogue connumdrum for us! I noticed on these the 6 wheel dot sets the pattern holes are larger for both the tractor cab and trailer sets. That could be due to more chrome be used in the production runs between these two items.
@***** Model World I'm pretty sure you're right that it's a T600. Can I ask how you're measuring the scale on trucks like this? I'm never quite sure where to measure them. When I've tried to look up real-life dimensions there are so many different cab and chassis configurations that I'm not sure which to use.