In this post, and in the 1973 Jet advertisement, you can read that the Jet was chosen as the watch for the Blue Angels pilots. Yours is probably from the same period, celebrating this collaboration.
Sherpa Jet Mk 3 (166-35-05)
Hello everyone I just picked up this lovely looking Enicar Sherpa Jet Mk 3, ref 166-35-05. I found no references to this model in the “Time for a Change” There are so few references to this model in total that I assume very few were made. I believe mine dates to the early-mid 1970s, and it...enicarforums.com
As of today, I’ve managed to collect 6 different serial numbers of this jet. Even if that doesn’t answer your question since it’s a different model from yours.