Many people are running the Jelco SA-750D tonearm on a Lenco L75 turntable.
The Jelco mounting base (30mm diameter hole required) will fit in the Lenco armtube hole and you simply bolt it to the top plate.
The Lenco tonearm pivot to spindle distance 210.8mm is very close to the Jelco distance of 214mm. You will not find another tonearm (at least under $2000) with a closer match. The few mm difference can be fixed by putting the cartridge further back in the headshell.
Here is a link to the Jelco SA-750D mounting template. It provides dimensional information.
Posted in: Jelco Tonearms and Accessories