NON-ADJUSTABLE THRUST ARM BUSHING KIT – Front Axle. Ideal for castor/length adjustable style thrust arms from other brands. Set of 4 The RSS Non-Adjustable Thrust Arm Bushing Kit will improve handling and response of suspension system. Eliminates unwanted caster changes in both front or rear suspension under acceleration and deceleration. AVAILABLE FOR ALL PORSCHE® 987, 997 (non GT#) 981, GT4, 991, 991 GT3/RS .