Per my theory that all transition year units have variants, I have come up with a few postulates to that theory, and a possible alternate explaination (or two)...
Many units were produced in more than one year, particularly from the first three years of units. The earlier the unit, the greater possible incident and number of variants. The longer the unit is produced, the greater the chance for mold variants due to wear.
As a mold is used, it gradually wears out. Once the mold wears out, it is replaced with a brand new one.
As production problems are discovered, the mold is changed to correct these problems. The longer a mold is used to produce units, the more likely a problem with the mold will be corrected due to parts having incomplete fill.
Plastic colors can vary due to mixing differences between the base and color ingots. Plastic colors can also vary between factory locations due to lighting and differing quality control, or due to an incorrect mock-up or guide sheet.*
Transformers increased in popularity from their inception until 1988 at which point they declined. Transformers popularity reached its peak in 1986 through 1987. As Transformers increased in popularity more factory production lines were utilized to produce Transformers, possibly even more than one factory.
*The above explains why there would be color differences irregardless of year. If they were produced at more than one location, it is entirely possible that the molds were switched out at different times, and the color mix could be a little off.
Interesingly enough, these theories could easily explain the Beast Machines variants too. If they have the wrong color mock-up, and they put the wrong color into the wrong molds, you end up with units that are backwards color-wise.
It's a start. Let me know what you think.- JoeBot.
A word on transition units: Like the Astrotrain variants, it may be possible to see a transition unit with one or more of the transition parts present. For example, the PMP gun modification seems rather rare, and may have been included with the very first or last units, but not excluseively with each. Let's say for the sake of argument there were 20 lines making Powermaster Primes. If 1 mold on 1 line is replaced after 90% of them are made, that would represent only 1/2 of 1% of the entire Powermaster Prime inventory with that difference. If there were 1,000,000 PM Primes produced (somewhat high, I figure), that would be 5000 with the variant. It is possible that well over half of any run did not survive to this point 15 or so years later. Therefore it is entirely possible that any variant falls within the destruction zone of units that never made it 15 years. Any variant could quite possibly be unique at this point...