Buck, here is some info in case you're still thinking about this.
Here's what you have as your final ratios currently (with stock 4.11 rear)
1st gear is 2.94 x 4.11=12.08
2nd gear is 1.68 x 4.11=6.90
3rd gear is 1.00 x 4.11=4.11
At 60 mph and 28 inch tires, your engine should be turning ~3000 rpm. At least mine always did.
And, if you go with 3.55 and keep your stock transmission, here is what you have:
1st gear is 2.94 x 3.55=10.437
2nd gear is 1.68 x 3.55=5.96
3rd gear is 1.00 x 3.55=3.55
60 mph and 28 inch tires should have you driving at 60 mph and turning ~2500 rpm. And I should mention you'll stay in 1st gear for about 26 feet (as opposed to the stock setup which will have you shifting out of first at around 16.5 feet). Obviously you will spend more time in 2nd gear also.
A take-off ratio of 10.5 is acceptable if you mainly drive flat streets and are not going to be using your truck to haul heavy loads. If you plan on using your truck to carry firewood or something heavy, I'd try to get closer to the ratio the truck was designed to have. From Chris's comment, he might agree. When Patrick first had the 3.55 gears made I went out there and we drove his truck one very hot Arizona day. I should add he had a 4 speed with a 3.11 first gear and this made his take-off ratio a bit over 11. He had also lightened his truck with monoleaf springs. He and I talked about it and he said he considered using the 4 speed with the 3.50 first gear to get the higher take-off ratio but the % drop-downs in that transmission were not as favorable as in the one with the 3.11 first gear. I thought he had plenty of pickup with the take-off ratio of 11 and change.
On the flip side, if you went with a T5 with the gearing shown below and a 3.07 rear end, you would have:
1st gear is 4.03 x 3.07=12.37
2nd gear is 2.37 x 3.07=7.27
3rd gear is 1.49 x 3.07=4.57
4th gear is 1.00 x 3.07=3.07
5th gear is .86 x 3.07=2.64
These ratios were calculated using 15 inch wheels with a tire diameter of 27 inches. 28 inch tires will lower them to almost exactly the stock numbers. If you look at the first 3 gear final ratios, you'll see they are very close to the original 3 speed ratios. This means in the first 3 gears of the 5 speed, your truck won't feel greatly different from stock and if you need to haul a half ton of firewood home, you'll have plenty of gear to do it. When you get to 4th, you will be effectively in your first overdrive gear with an overall ratio of 25% less than your 4.11 rear end. That's significant relief for your over-revved 6 and you could cruise in 4th at 60 mph at about 2300 rpm if you wanted to or you can use that gear for hills or passing if needed. When you get to 5th gear, you'll be 39% lower than the 4.11 and at 60 mph, your rpm (again with 27 inch tires) will be about 1970. I don't believe you want to go below 2000 with the 235 for a cruising speed, so 1970 rpm is what I'd consider the bottom line.
Good luck!
Jon
