That's the first evidence I've seen that those prototypes actually existed.
I've seen both 85 and 86 dates quoted. I suppose I should take the neck off... I only took it off once, long ago.
Also, I thought production was nearer 500 than 100; unfortunately most information on these basses is nearer myth than legend.
What is rarely mentioned is that with 40-100 strings on it is very nice to play. I rarely gig it, but it was my main bass in the early 1990s alongside a Hohner B2.