Personally, I would go right to the 5.38:1 if you are running the 42RLE automatic. Mine is my daily driver and can't imagine anything less with the 3.8l engine, 35" tires and the automatic.
Mike.
On edit, the last guy's I did he was going to run 5.13's and I had him drive mine. He then had me install the 5.38 gears and has been very pleased. Just trying to give "actual" or "real world" information rather guessing or merely looking at a chart. I too started out thinking of installing 5.13's but drove a guys with 5.38's and that was the deciding factor. Had mine in for 4 years now and over 50k driven miles, another 15k-ish of being towed behind our coach.