My oldest factory piece, still in use(since 1980): a Magnepan Unitrac I, tonearm. The only change made to that, was creating an adapter, to allow upgrading it’s interconnect cable. Now mated with a Soundsmith cartridge, a golden(maybe platinum) combo. Also, circa 1980, one of my customers requested an actively crossed over pair of 10" driver, folded, 8’ transmission line woofers, to mate with his Acoustat Model IIIs. After building his and hearing the results(with a modded Hafler DH-500, driving them), I built a pair for myself. They’ve been providing fast, dynamic/impactful, tuneful bottom end for me, ever since. A few years back, I swapped out their Milos Nestorovic sourced, 10" drivers, for Seas L26RO4Ys.