The taller gears (3.42 is "taller" than 4.10) will make it slower off the line. It might make it a little more user friendly, but I wouldn't think it would be a considerable difference. Why not just get 3.42's for your current rear end? If you change to the Colorado your brakes are different again, you have to worry about mounting and all that... Seems like not the best way to make the change.

Is there a reason you want to use the Colorado? The width of the rear end is also narrower than the K5.

I know that you've been having frustrations with your truck, I don't think this is the right way for you to get taller gears.

1946 GMC Pickup - S-10 Frame, 455 Buick, TH400, original patina.

My 46 GMC on Photobucket