Need help with this vacuum reading

Ok...found the answer on a.....:pukel: CHEVY site! LOL

You turn BOTh rear tires at the same time.

I made a mark on each tire, referencing it with the backing plate...then made a mark on the oke, referenced to the chunk.

Laid under the back of the car and rotated each tire at the same rate, slowly and together and I got 2 and 3/4 turns of the shaft to one turn of the wheels.

SO I definately have a 2.76. Hey, at least I know that for sure now! :cheers: