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LS short box · 02-19-2021, 07:10 PM

Check over on LS1tech.com for info on flex plates. Some need spacers to match the trans.
Your 2003 should be a 24 tooth crank reluctor. So one ECM for the engine and trans. If you haven't done this before I would buy a ECM and harness from one of the vendors. They can give you a basic tune to get you going.

02-19-2021, 07:10 PM	#10
LS short box Registered User Join Date: Jun 2015 Location: Carlos MN Posts: 1,927	Re: Questions about 6.0 engine/Trans Check over on LS1tech.com for info on flex plates. Some need spacers to match the trans. Your 2003 should be a 24 tooth crank reluctor. So one ECM for the engine and trans. If you haven't done this before I would buy a ECM and harness from one of the vendors. They can give you a basic tune to get you going.