Disclaimer: My opinions are just that – Opinions. I have done extensive research on Vintage Thundercats to include different producers, different distributers, and various variations. I hope that the information I provide helps other collectors in finding their “holy grail”.
It has become extremely apparent that (although sometimes small) there is a distinct difference between early and late 8 backs. The most noticeable difference will be the mini catalog. The later 8 backs have the mini catalog. You can also tell by the assortment number.
Villains – Early (3515) Late (3545)
Heroes – Early (3500) Late (3545)
And of course you have the “energizer” Lion-O and Mumm-Ra (3527)
Attached is an example of and early and late Monkian, notice the early version has the red chain. There are seems to be differences for many of the characters, both Cheetara and Tygra were available early with or without companion, later they could only be found with companion (until the 14 backs came out) There are various variations of Lion-O and Mumm-Ra both early and late, and this Monkian. My theory is that early Slithe and Jackalman may also have slight variations.
Please feel free to discuss your thought on this subject

