I personally have had the 35’s and 4.10s as well as the 33’s and 3.73s. They run within about 50 rpm of one another and imho it’s the best dd/towing setup for a 7.3 auto. At cruising speeds (70 mph), you’re into the power curve at that point and not under it. But not too much into it that mileage suffers empty. But far enough Into it that if you ask it for more when towing, you’ll get a response immediately.
It comes down to what you want for looks/height and use. Either is a great combo.
I see they are very similar in RPM/MPH. If I was starting from scratch I think I would probably go 33&3.73, but being that I already have a wheel and tire combo with low miles, guess I'll stick with 35s.
I did swap in a 4.10 axle just to road test before going through with a regear on mine or full rebuild of another axle. I haven't logged any highway miles yet but on local roads at 50 to 60mph, it's a huge improvement in how it runs. Truck is clearly within the low end of the turbo now, instead of below it.
Sounds just like my 97 CCSB 4x4 with 3:55s (35” tires) and Auto tranny.... under the turbo... (stock turbo mind you). Went to 1.0 exhaust side and can think the .91 would be even better. Felt like I was either on the fuel for boost... on the brakes or coasting with the auto. Swapped to ZF-5, so much nicer. Current truck in sig is nicer 4:10s 37” tires with ZF. FFD 205/30s and Jelibuilt tunes sparked it right up. Thinking 364.5 with .91 would be beauties... for what I do.
Thanks for up dates fellas.. cheers stay safe.
I would love another gear or 2. I would be tempted to do a zf6 swap but I already have a BTS, and I don't know if my wife can drive standard anyways. Really want the simplicity and driveability to throw anyone the keys and not worry about EGTs, clutch, etc.
Are you still on stock turbo?
Just to throw this out there, if you are going the 3.73 route, have you thought about the 05+ axle swap? Most are 3.73. That way you aren't setting gears, and you get to "upgrade?" to a coil solid axle, bigger brakes (front and rear) and I believe tighter turning radius. Not sure how it compares assuming you still have the TTB front end. If nothing else, gives something to research. It would also force a rim change I believe, and possibly a steering gear? Not sure if the brake master should be swapped also to match calipers, assuming you have rear drum? Just a thought. Maybe a rabbit hole...
Thanks for the input.. I already have a Dana 60 with Super Duty leaf springs, so an 05+ swap is out. Maybe if I find a CCLB DRW OBS, I would then love to do the 05+ swap.
For the rear, I was going to rebuild a OBS DRW axle to get rid of my spacers. I have 2" spacers on each side of the rear, to match the front axle track width. I'd read somewhere that a DRW axle was 4" wider, and my dad had a parts truck with one, so that's what I swapped in to test 4.10s. Not sure where I got that info but the DRW axle is 7" wider than a SRW..
Looking for a Super Duty rear axle now, as the track width would be right, would have disc brakes, etc. Just have to get a price on machining the hubs to be 8x6.5.
