3.55 will increase your speedand drop your rpms, and its not a bad option. Your truck would look stock, and your existing rear and torque tube would be overhauled.
If you found a the pumpkin from a 55-62 rear, it will interchange in your housing giving you an open drive 3.90 ratio. Some welding will be required. the 3.90 open rear coupled with an OD transmission will drop your rpm a lot more on the freeway. The 3.90 gears are better for acceleration than the 3.55 gears.
