Al, may I suggest that you ask this question in the right forum topic - you are asking about tow vehicle information under Bighorn electrical. Many folks in the forum do not look at all new posts, but only those of specific interest.
When you repost this, you need to provide more information about your tow vehicle then just a rear-end ratio. For example, a Dodge 3500 would only have a GCWR of 21,000# (at least for a 2006), whereas a 4.10 goes up to 23,000#. A 2500 could be less.