[Mark42]

I weighed the steel shaft, and it comes to 19.6 lbs. I contacted three different people who listed aluminum drive shafts part number 12564003 for sale, and asked them to weigh the shafts using a bathroom scale. The weights came in at 10, 11.5 and "almost" 12 lbs. So I am going to make the safe assumption that the documented weight of aluminum drive shaft part number 12564003 being 11.5 lbs is correct.

So there is an easy 8.1 lbs weight savings over steel shaft part number 12556670 by using the aluminum shaft.

The other part numbers for aluminum drive shafts are:

96 - 99 Fbody w/ GU5 have shaft P/N 12559525
00 Fbody w/ GU5 have shaft P/N 12564003
01 - 02 Fbody w/ GU5 have shaft P/N 12564004

It is interesting to note that SI says if imbalance from drive shaft cannot be corrected by 180 degree re-install for 12564003, to use 12564004.

BTW, the lightest aluminum drive shaft is the 1LE 2.75" diameter shaft weighing in at under 10 lbs.

Hmmm. how much do those 17" vette wheels weigh I want to add? LOL!