Hello Rick
When you say "drop", does that mean you want a lower and slower (with more grunt) gear ratio, or a higher and more drive able highway cruising gear set?
A typical two speed rear end will get you an extra low range for more pulling power, but will not help achieve any better highway speed.
There are other options such as replacing the ring and pinion, but it is not cheap, and may not get you enough improvement for the dollars spent. It will most likely be more economical to switch out the entire rear axle with a newer one.
Check out the tech tips for more info on this subject.
Welcome to the Stovebolt (were glad to have you)
John
