Vince, the Formula is 3420lbs. Not really that heavy for a car that big.
Scott, Wease on here ran one in his '98 Formula M6 years back. The posi and gears are stronger if they're the right type, and can be built to handle much more than the 7.5" 10-bolt ever will.
I'm picking it up Saturday, you can come back after I get back to look at it and pick up that article of clothing.