I saw a couple of posts about Tachometers recently. Ebay has one a hand held 380184347
Saw a couple of cubs also.
A 1954 no bids 384100910 says must be preapproved but does not say where the tractor is .
Another 3840912049 no year. Located Plumsteadville PA
Another 3840974461 1948 with accessories $ 3500
Ihope this helps some, If not at least I tried.