Okay @nightmareB4macross, you were right... it's really cooking in here! The mythical Joons 1A! Just incredible. Since we're on the topic of Joons, just last week I found that the "1996, Patriot" colored Joons leg fin had either blue paint, or left blank. I had my original from the late 90s that I converted to a 1S, with Jetfire arms and legs, repainted most of the valkyrie to a Max blue. Fast forward to a month ago... worked on reverting that same Joons back to its original colors and parts, minus the 1J head... which had been traded away over 2 decades ago.
Here's the back of the leg fin from my originally purchased one late 90s. Blue paint.
Here's one from a listing online. Blank.
Here's a friend's one from Wisconsin. Blank.
Here's a friend's one from Northern California. Blue paint.
Seems like the ones with the blue paint on the back of the fin also have the top quarter of the outer leg painted blue originally, then painted over completely with red paint.
I finally completed the "restoration" of the "converted to Max 1S Joons that I had... he still has a 1S head, inspired by Alex's earlier pictures from this thread.
Hmmmm, I also found this listing on the web... it was sold in 2017? Claimed it was not tampered with... could this have been an end of the run, just get rid of left over stock version?