You currently have an effective ratio of 3.73 with your 35s. You would need 4.56 gears to give you the effective 4.10 ratio that would be best for a truck that constantly tows.

 

Gee, it's almost as if someone tried covering that base already with the OP and got shot down in the process

 

Kind of difficult to compose this and convey my thoughts because this isn't verbal communication so you can't hear my inflection, so I hope you can "hear" the clarification intent and you don't "hear" a corrective tone, but there is a bit of difference between what Tor and I posted and what you posted.

Your suggested higher R&P gear size was for an overall multi-usage daily driven vehicle, where Tor and I made the distinction that for those same R&P sizes, the higher numerical gear would be better suited for something that does more specialized duty (like towing, or a ranch rig, etc), but not so much for a daily driver.

A lot of us come from a hot rod gasser lifestyle, so we know what gears can do for a car, especially when dialing in a car for the power curve as you cross the line at the big end. But these diesels are a little bit different when gearing meets real world effectiveness for a multi-use rig because they can't rev as high.

That last paragraph was not meant for you Dinkopotamus because I know you already know that. It was meant more for the person who comes across this thread and doesn't know about gears and the 7.3L and how they interact differently than do gears and a gas powered rig.

Most people who are like Tor, and who followed the same advice Tor was given years ago, find they prefer having the same effective gear ratio (or very close to it) as came from the factory, as opposed to a higher ratio, even one only slightly higher.

Stewart

 

I get all that, my suggestions were based off the 35's, effective ratios, and the heat and humidity in Louisiana which absolutely obliterate power and torque figures. The fact that the OP specified the trailer would be maxed or slightly over the max weight. Coupled with the slow-pokey nature he tends to drive, and I have seen more than one person wish for a higher effective / gear ratio after towing heavy... If it's a tow hauler that will be yanked frequently, then for me personally the steeper gears make more sense across the board PURELY due to his geographical location and the weather/climate influence. The RPM difference is negligible, and the higher ratio would help a little more for that much tow weight.

Forums make things hard to convey without the actual audible tones and inflections that make conversations what they are, no hard feelings or insults taken from you nor from Razzi.

 

A lot of people say 4.10s/35s is a great all around combo for a 7.3 that has multi uses.

But my personal experience says it should be lower(4.56 or 4.88) if your going to tow heavy (10,000+ lbs) at 65 mph and above. 60-70 mph is a shift zone on my rig it seems. It either wants to lug in OD, or rev in D

 

Ha, Forgot I even posted in this thread, That's what I get for using a smartphone to post from, tiny fonts .... Got the rpm by selecting the wrong transmission. Doh