This is a Delco 37MT Starter (12V), Using DE Housing #1986333, a 12-T Drive, a 1/2" Battery Stud, and No Ground Studs. The 6290 is the Same Unit With a 3/8" Battery Stud and the Opposite Lever Housing, The 6386 is the Same Unit With 1/2" Battery Stud, But a Lever Housing for Opposite Drive Opening. Also, the 6384 is the Same Unit, But With a "Jump Start Protection" Solenoid, While the 6385 Has the Same "Jump Start Protection Solenoid", and Also the Lever Housing for the Opposite Drive Opening. The 6403 is the Same as the 6393 With the Addition of a Field Case Ground Stud, While the 6403 is a 6402 But With the Opposite Opening Style Lever Housing. The 6394, 6399, and 6400 All Share the Same Major Components Also, But Have the Ground Stud Mounted in the CE Cover.