Built in tiny numbers during the 1960s these 10-inch and 12-inch lathes were of an almost completely different design to the original L Models and with features that foreshadowed the modern M Series lathes of the 1970s. The one feature that distinguished the models from other Harrison was the use of a face lever on the apron to engage the power sliding and surfacing feeds. In line with styling changes to other Harrison models, including the far more common L6 Mk. 3, were: a flat front to the headstock, a square-looking, totally-enclosed "dial-type" gearbox with three control levers ranged in a line along its top edge, a raised section at the end of the top slide casting to allow the fitting of a larger micrometer dial and, on the 12-inch only,  a spindle-control shaft beneath and parallel to the power shaft with control levers on both the right hand face of the apron and just outboard of the screwcutting gearbox. The spindle was bored to pass 1.375 inches and carried either a L00 or D1-4" Camlock fitting.