Quote Originally Posted by bobsmith380 View Post
They have different part No's. 253 is set at 6 degrees before TDC and 308 is 8 degrees before TDC.
Yeah fair call. But GMH lists different versions for automatics and manuals and those with cruise control. So stating 253 or 308 means nothing if you don't know
auto, manual or cruise control models. The upshot is they all fit both engine sizes and need tuning to suit.