I have no doubt that Smok][n did the install himself, and I have no doubt that he got extremely lucky, based on what he has revealed thus far about his installation.
I also have ZERO doubt that arrabil has done this the correct way and knows first hand EXACTLY what he's talking about.
The closest I got to a gear change is simply swapping out my 3rd member on my Mustang. (yes, I had two of them each with a different gear). Since my mustang is putting down 3-4x's what our trucks are, I leave it to a friend who does this for a living to set up the 3rd member.
ALLCARFAN,
My advice is to be 100% sure that who ever is doing this gear install for you will correct anything that goes wrong with it at no charge (provided it's related to workmanship of course).
Since these trucks are not laying down crazy HP numbers, any competent backyard mechanic can do this with the right tools and experience. But as arrabil stated, don't guess or take short cuts, cause the results could easily cost much more in the end. Smok][n took the dive and appears to have surfaced unscathed, but he has told us this already. If you have ANY hesitation, let a professional do it.
BTW, I just sold my 4.30 R&P on NMRA forums. It was a Yukon and was very dependable. I currently have a

MOTIVE

3.50 R&P installed in DetroitLocker now. (3.50 due to all the torque the motor now makes due to the sc'er). So far, so good on the Motive's.......