I weighed my (LT1 style) T56 today, here's what I came up with...

126 lbs - Tranny (w/shifter, fork, and sensors, no fluid, no bellhousing)
6 lbs - Bellhousing
18.5 lbs - Flywheel (I was told it's a lighter LT4 flywheel, but I can't confirm)
18.5 lbs - Spec Stage III clutch (disc AND pressure plate)

169 lbs - Total

Just thought some might like to know.