Air Lift Fittings 21738 Air Lift Company has developed dependable air spring suspension products since our inception in 1949. All our efforts are spent ensuring your safety and comfort by designing, engineering and manufacturing the highest quality suspension products. Bushings Bushings; 3/8 in. MNPT x 1/4 in. FNPT; Air Lift Bushings- 3/8in Mnpt X 1/4in Fnpt