Huntindog wrote:
It is a choice. Do you want better performance when towing? Or better MPGs when empty?
The different rear axle ratios WILL make difference. Neither choice is "wrong" or "right".
The 3.55 will have the effect of making it a close ratio trans... IOW, the motor will operate at it's powerband peak more. This will change the personality (so to speak) of the truck, and it will just make for a better tow, and probably a little better MPGs when towing. At the expense of sacrificing in MPGs when empty.
When deciding, you gotta consider just how much you tow, and how demanding your towing conditions are.. There is more to it than just looking at rpms @ a certain speed. How you get to that speed matters as well.
IOW, if you have two indentical trucks/trailers with only the rear axle ratios different. And drive them both.... One WILL impress you more. In this case, the 3.55 truck.
Unhitch the trailers, and the difference is mainly gonna show up as better economy for the 3.15 truck.
Your money. Your choice.
Yes. That's the whole point of this post. I have already discovered with 8,000 miles of towing that the 3.5 EB with the 6 speed 3.55 with the 14.80 first gear ratio does a fine job of towing my 6600 lb. camper. It is "good enough". In fact, it's great. I don't need a lower first gear. I see no reason why the new 3.5 EB with the 10 speed 3.15 with the nearly identical 14.77 first gear ratio will not do an equally fine job. But the 10 speed gives the advantage of lowering the engine speed in the top gear by 19% by lowering the gear ratio from 2.45 to 1.98. My towing miles are 8,000/105,000 = 7.6% of the truck's total miles so far. The low range gearing power is good enough and I would be sacrificing nothing there with the 3.15 ten speed, and the better mileage would apply to many more miles. I don't see a downside.
