Regards, Lewm:
Thanks for setting the record straight.
Several years ago a cache of the LPM 4xx cartridges emerged from a vendor who became referred to as "the Italian seller". The cartridges were shipped in the original packaging. Examination of the enclosed literature clearly describes the 400 series as IM. The tri-pole configuration, although reconfigured, remained a design element and is speculatively responsible for the slightly more forward presentation of the later series.
A belated response to Islandmandan (I'd not seen this thread until now): I find that when the LPM carts are mounted on a metal headshell a cartridge isolation device improved definition on my rig (EPA 250 or 501 TA wands). Wether this is due to increased mass or diminished acoustic / mechanical feedback I cannot say.
Lewm, the LPM cartridges mounted on an Ortofon LH-8000 Japanese oak headshell introduces a slight resonance bloom at about 2k Hz. This midrange junkie finds it pleasing. A purist might prefer the Saturn V.
Peace,