Having never seen one, the information to the right, the photo, and the review below come from Paul Strange of the UK. Few if any were sold in the USA.
“This model – a portable and powerful Nihon-Hammond solid-state Leslie using a slightly modified 122 horn and simulated bass rotor – was introduced in the UK in the early 70’s, probably for the B200/B400 series. [Nihon-Hammond was a collaboration between Hammond and Japan that produced several Organs and Leslies in the 1970’s — T. Thompson]
Weighing 50 kg, it’s a compact design (605 mm wide x 460 mm deep x 668 mm high) with two channels (rotary and stationary) and has three inputs – an 11-pin interface (for XB/XK series organs) and two 1/4″ input jacks for use with other instruments. Four separate amplifiers power its four speaker sections. The rotary channel – via the 11-pin or a 1/4 in jack – is fed through the top rotor and BBD modulator/15 in woofer. The straight channel – 1/4 in jack only – is fed through the 15 in woofer and two additional horn tweeters. The 310 – now quite rare in the UK – makes a useful match for the Hammond XB2 and XK2. A very portable package, it can sound a bit strident, so for jazz and blues use a mellow setting; for rock, increase the treble slightly and remove the front louver panel.”