LS Crankshaft Swap Guide
Be careful when purchasing a flexplate and bolts. Reason why, there is a special year ('99-'00) 6.0L LS that had a "long" crankshaft. That means the crankshaft projects .55" inches from rear cover lip, compared to the .13" inches from the standard length crankshaft. This does not seem like alot of difference in measurement but it is the difference between your swap mating up or not. With the standard length crankshaft you need a dished flexplate & NO spacer. With the long crankshaft you need a flat crankshaft & NO spacer. The spacers are for non-LS transmissions.
What this means to you?
Mating whatever transmission you are using to your LS engine can be a very simple process or a very difficult one. Making sure you have all of the parts you need for your exact application will save you a ton of hassle. A common swap is a 6.0L LS based engine, for their power and reliability, but in the '99-'00 they came with a "long crankshaft". That long crankshaft will only work with a flat flexplate compared to the dished plate on standard length crankshafts. Just do your research on the engine you have, try and get the RPO code for your engine, or the VIN (Vehicle Identification Number) off of your donor vehicle and any GM dealership would be able to provide you with a build sheet which would have all of that information on it. Please refer to the guide below to see the differences and the ICT Billet parts needed
Feel free to Contact Us if you have any questions!
See link to shop ICT Billet Flexplates