The problem with those are they are designed for the old school small block engines, not the GEN III LSx version engine your trying to put in. I'm not positive but I highly doubt that they have the same mounting hardware.
Look at this page and you can see that they clearly distinquish that there is a difference between the small block and LS1 mounts.
http://www.jcwhitney.com/autoparts/Product...Ntt=motor+mount
Don't know if you've read through this yet but I'm sure it will help you.
http://www.fullsizechevy.com/forums/...d.php?t=144116
Looks like you'll just need to find yourself a set of 4.8/5.3 mounts. Not sure what the registers are that they are talking about.
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