Hey tbam,
With the 4.70:1 gears, you should be around 90:1 in low range. I've never seen an auto in low range, but I would put money on the 4.7's to be slower on flat ground. Now going down hill, I 100% guarantee the 4.7's to be much much much slower and you do not need to ride your brakes ever where you go!
BigMike
