Get the 4.30 rear end for the 7.3 gasser.
It is perfect with our Northstar camper.
If you get the 3.73’s, even at freeway speeds you will not be able to use the top 2 or 3 gears without lugging below 1500 rpm unless you are going 85 mph. Maybe the trans will not let you lug down below 1500 rpm.
I thought the same as the diesel guys above, until I actually owned and had time in the saddle with an F-350 with 7.3 gasser.
I wrote a long response to both questions, but it disappeared into the ether.
I found it, but the site says, “Forbidden” and it won’t load for some reason.
I added it here:
Brett: I do have a 2020 7.3 gasser Ford F-350 and have some real world experience with it. I’ve been in both camps (diesel and now gas) and from my own diesel experience would have suggested what the above boys are suggesting for gearing if I hadn’t driven the 7.3 gasser. But…..
I have the 4.30 gears and would have no other for our load: 2020 N* Laredo SC. Weight (not dry weight) with full water and propane: 2350 pounds. That brings our traveling weight up to about to around 3300 pounds. The payload is over 4000 pounds, so we’re not close to overloading especially with all the suspension goodies. I just ordered another pair of upper overload leaves and will add them into the mix. With only Sway Stops, a factory anti sway bar, Rancho 9K shocks, and 2 upper overload leaves, I submit I’ll be very close to a fine tuned compromise between too much sway and a harsh, gerky ride. Our factory GVW is 11,300 pounds. The empty truck weighs 7215 pounds with that light little gasser engine. A 6.7 Ford diesel engine weighs at least 600 pounds more.
I find the 4.30’s to be just right for the engine torque and the way this old man bumbles around and drives; namely around 62 mph on the freeway with an egg under my foot on the stupid pedal. If i need instant power, the Godzilla supplies. The engine is right on 1500 rpm in 10th gear at 55 mph. This is the sweet spot for mpg.
I think you will have to lock out gears 9 and 10 and possibly 8th if you get the 3.73 gears. The transmission may automatically do that for you with 3.73’s. I’ve had plenty of diesels and would have lower numerical gears if I were driving one, like 3.31’s, 3.42’s, or 3.55’s. I did have 3.55’s on my 2001 Dodge Cummins/6 speed manual but changed to 4.10’s when I put 35 inch tires on it.
Brett: AFA your proposed load with a 3300 pound camper, I think you will be above the payload rating right away if you use the, “add 750 to 1000 pounds of people and stuff” rule. In that case you will need more suspension support than I have to survive, or consider a DRW truck. We have a saying in the TC biz: “No one ever complained about having too much truck.” It’s a perspective thing. Higher rated tires to some with a higher than 4000 pound capacity. Much better shocks. The factory shocks are junk. I dumped my factory Ranchos the first week I had the rig. A big wig sway bar with the 1-5/16’s inch bar. That will give you some backbone.
If i were you, I would get on FTE (Ford Truck Enthusiasts) facebook page and browse the RV-truck camper section to see what Ardvark and others have done to wrestle a heavier camper.
Jamie: You would do well to pretty much go the route I did with the 7.3 gasser.
2020 Ford F-350 XLT FX4 4WD SRW SB SC 7.3L Godzilla Gas TorqShift 10R140 397 amps dual Alt dual batts Frnt Dana 60; Rr Dana M275 E-locker 4.30's 4580/4320/4066# payload 7243# curb wt. 11,300# GVWR 5-er prepped. 2020 Northstar Laredo SC, 12v compressor fridge, cassette, 320w Solar sub zero insulation.