I have owned a 2005 997S since 2015. This car now has $66K miles. It had a Porsche factory replaced engine in 09 @ 18,686 miles (not IMS failure). They replaced it with a 997-100-997-"BX" engine. Can anyone tell me what the BX stands for? Was this an '07-'09 engine? I know the original '05 997 3.8s were 997-100-997-0 Thanks!