1960's and 1970's - 3 1/2 Inch Wide Springs
Early applications featured bronze bushings for both conventional and (COE) configurations. These types of springs were phased out by the late 1960s or early 1970s. In rare instances, springs with threaded (TB-70) bushings were also utilized, though only in very limited applications.
TB-70 springs typically mirror these bronze-bushing springs in all aspects except for the type of bushing used. When necessary, TB-70 springs can be substituted for RNI springs, as they share the same eye size