Could'nt tell what transmission you have but I'm assuming a 5sp because of dana80. This govkit will make it much easier to accelerate fast through the gears because of the wider powerband. I've tried both and find the 4k kit a significant improvement over the 3k. Especially with a 5sp. It shouldnt really add any noticable power though. Good mod, you'll like it!
With the stock auto it makes an improvement too. The revs get up to where the torque converter can pass more power to the wheels instead of slipping.