As I have been learning about some of the history of Estes ground support equipment between my leaving the hobby in the early 1970s and my return about six years ago, I've seen all sorts of mixtures - so I'm not surprised some Moon Mutt sets had the black EB and some had the more recent sealed (so you can't get exposed to the lead on the back of the continuity lamp) yellow one.

Also, in the course of my getting a bunch of old GSE from eBay I've gotten quite a few motors shipped to me and seen many listed sometimes by themselves despite eBay's supposed policy.

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Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE