EMPI makes 2 different qualities of shock absorber:  Oil-filled shocks, and Nitrogen gas charged shocks.  The oil filled shocks are a direct replacement for factory shocks.  The nitrogen gas filled shocks offer smoother performance without the "flat spots" associated with oil shocks, and are generally longer lasting.  Gas shocks tend to vary with road conditions better, as well.

If your car is lowered with drop spindles only, or with adjusters and drop spindles, use the STOCK shock.  If it is lowered more than 2" with adjusters only, use LOWERED shocks to prevent the shock from bottoming out against the shock tower and damaging either itself or the car's suspension components.

Ball Joint Shocks fit 1966 and later Bug, Ghia, and Thing front ends, whereas Link Pin shocks fit '65 and earlier.   Rear shocks fit all years Type 1 and 3, and also fit rear of 68+ buses.