Charlie
I think you mean the single rear wheel (SRW) 3500. See dieseltruckresource.com web. As others are saying it looks like with towing duties mpgs is a toss up but the 3.73 may give a couple better mpgs when empty. I notice operators on hotshot webs prefer the 6.7 with 4.10 gears with the auto as their hauling max loads and run very little empty.
Jim
'03 2500 Dodge/Cummins HO 3.73 6 speed manual Jacobs
'97 Park Avanue 28' with two slides
Mine is an '04, but have run 18-19 mpg empty (if I keep my foot under control), and have never run UNDER 13 in tow. I know, the 5.9's get a little better mileage, and mine is a dually, but this a matter for reference. Good luck.
Lee
2004.5 Dodge 3500 DRW QC, 4x4 LB, CTD 600 ,auto,4.10 , Prodigy, 05 Cedar Creek 36 RLTS w/ lots of bells & whistles .Honda 3000 genset. Mrs Greentow & Missy, Shih Tzu with an attitude. USA(R). 30+ years in the Fire/EMS service. CCRVC #29, GS Life member
I have a 06 2500 CTD with the 4;10 gear.Non-towing I get 15 to 16 mpg,and towing a 8000# TT I get 11.5 to 13 mpg.It has 16K on it and everyone keeps telling me it will get better once its broke in.I sure hope so.
2006 Dodge Quad-Cab 2500 CTD,4;10 gears,pulling a Forestriver Flaggstaff 831qbss
See what it would cost to change your tires from 265's to 285's.
The slightly taller tire will effectively drop you down to around 3.8 axle.
Don't forget to change the spare too!!
Personally I would just leave it alone...I don't think you would see very much diff in highway mpg.
If you are talking a new rig with the 6 sp, you have to remember the DOD will net you a taller final drive ratio than a 3.73 with the 5 spd auto that was on previous rigs. If it were me, I would take the 4.10 over the 3.73 if I was getting a 6 sp, if a 5 spd auto, or rig without the OD, then a 3.73. A 4.33 setup in DOD would have the same final ratio as a 3.73 in OD. Your MPG's should still be reasonably decent even with 4.10's.
Just my 02, remember how much you really paid for all these suggestions.
marty
05 Chev CC D/A LS Dooley
92 Navistar dump truck, 7.3L 7 sp, 4.33 gears with a Detroit no spin
00 Chev C2500, V5700, 4L80E, 4.10, base truck, no options!
92 Red-e-haul 12K equipment trailer
3 Single axle utility trailers