It's the top model from a line of cartridges that Empire brought to market in 1980, just after the company had been sold to E. Benz. You'll find them collectively called "Chunkies" in this thread because of the odd (compared to Empire's earlier models) styling of the mounting cap. The original official name was "Dynamic Interface".
On the inside, they were the same design Empire had been using since 1966, but much lighter, a very welcome improvement, and with overall better styli. You can think of them as an evolution of the old 2000E series, but with tech borrowed from the 1979 EDR.9 flagship, which was a summation of everything Empire had done up til then.
The 600 LAC isn't state of the art in some respects (effective tip mass, for one), but it's still a pretty serious cartridge. The cantilever is tapered and lightly dusted with vapor-deposited boron, and its high-frequency resonance is tamed by using a tiny internal inertial damper-- a needle within the needle, if you will-- instead of mechanical damping by the rubber suspension.
Here's an illustration, taken from an EDR.9 ad, showing the inertial damper partially withdrawn from the cantilever:
The "LAC" diamond is a line-contact type.
When simply thrown together, these things don't necessarily add up to great sound, but Empire specialized in making all the parts work together, so you have a cartridge that sounds better than its spec sheet reads.
The 600 LAC's body isn't rare, but it's not common. You can't put just any "Chunky" stylus in it and get a flat response curve.
The 600 LAC had a near-twin, the boron-less LAC 75.