"VERTICAL GYRO PB20N AUTO PILOT; SUPPLIED W/SABENA SUSPENSION MODIFICATION, WHICH REMOVES THE GYRO FROM THE BOTTOM BASE OF THE ASSY AND SUSPENDS IT FROM A RING RAISED ON 3 LEGS; THIS PREVENTS THE GYRO FROM BOTTOMING OUT DURING HARD LANDINGS AND VIOLENT PITCHES; MOD IS APPLICABLE TO THE FOLLOWING BENDIX VERTICAL GYROS: 866-1A; 1B; 1C; 2C; 2D; 897 AND 911; 15885"