Here we have a steel weld-on oil, rearend gear lube or fuel filler neck assembly and steel weld-on drain plug. The steel drain plug fitting and plug are 3/8" npt (pipe thread). This 1 1/2" o.d. steel filler neck has a 1 1/4" i.d. and is 1" tall by itself or 1 3/8" with the cap installed.
