Hookem, if your present gear ratio is 4.11, changing to 3.55 will not vastly increase your freeway cruising speed. I did that conversion on my '36 Chevy pickup recently and it is definitely an improvement but the change is 13.6%, not a huge amount.
The 3.55 gears were used in some '50-'54 Chevy cars so if you're open to using a car rear axle in your truck you won't have to buy that expensive gear set from Patricks.
