1928-1931 Axles have a uniform curve from end to end.  Spring perch bosses are 2 1/4″. Axles are 51 7/8″ in total length. Radius Rod Centers are 36 1/4″.

1932 Axle is often referred to as ’32 Heavy axle and has a slight drop. These are the preferred axle to drop. Axles have a wider recess at the ends between the spring perch bosses and king pin bosses. Spring perch bosses are 2″. Axles are 51 3/4″ in total length. Radius Rod Centers are 39 9/16″.

1932-1936 Axles are the same dimensions as the ’32 heavy axle, but have narrower recesses at the ends between the spring perch bosses and king pin bosses when compared to the 32′ heavy axle. Spring perch bosses are 2″. Axles are 51 3/4″ in total length. Radius Rod Centers are 39 9/16″.

1937 V8-60 Axles have hollow forgings. They are a tube axle.  They are flat along the front and back. Lightweight and not recommended for use with heavy vehicles. Spring perch bosses are 2 1/4″. Axles are 50″ in total length. Radius Rod Centers are 38 1/2″.

1937-1948 Axles are not recommended for use with early vehicles because the distance between the kingpin and spring perch bosses is narrower than earlier axles.  The shorter distance does not allow them to be dropped as far as earlier axles and they don’t look as good. 1937-1941 Spring perch bosses are 2 1/4″. Axles are 49 7/8″” in total length. Radius Rod Centers are 38 1/2″.  1942-1948 Spring perch bosses are 2 1/4″. Axles are 52″” in total length. Radius Rod Centers are 40 3/4″. 1948 axles have an extra hole in the beam for tube shocks.