The 6489 Became Original Equipment on GM Trucks in 2001, Although Delco Also Uses It to Replace the 6488 in 1999-2000 Applications, Because There is a Problem With the Mounting Ear on the 6488 Breaking. When Replacing the 6488 With the 6489, Use Long Mounting Bolt #12561387 (Not #12561848, as Previously Thought - This is the Short Bolt) in Place of the Short Mounting Bolt Removed. GM Has a Service Bulletin (#03-06-03-001, Dated 1-2003) Which States That he Starter Motor May Continue Cranking After the Key is Released. This is Because the PCM Controls the Cranking of the Starter and Will Allow it to Continue Until Either the Engine Starts, or a No-Start Time Limit is Reached. This is Normal. We Have Been Made Aware of a Possible Fit Problem When Trying to Install the 6489 in Place of the 6488 on a 1999 Chevrolet Silverado With the 4.8L Engine (2WD Model at This Point). The Installer Says There is an Obstruction Which Forces the Use of the 6488 Because the 2nd Long Bolt of the 6489 Will Not Allow for Proper Mounting.