Tesoro had the 3 3/4 turn pots custom ordered in bulk. Extremely hard to find them in the resistance value Tesoro used. Ten turn pots are easy to find, low price but a bit big.
10 turn give a finer, more precise tune than 3 3/4 turn.

I happened to come across some 3 3/4 turn pots at one point bought a few. Again, some one custom ordered these. They had smaller 1/8" shafts vs. the 1/4" shafts.

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I dig it with a Nokta/Makro product-Legend
and Blisstool V5 The Beast