You’re in luck. Unles you have a F450 or F550 you dont have a true Dana Super 60 (256mm ring gear and 7,000 lb GAWR). You have the same axle that your 05 had - a high pinion reverse rotation Dana 60. It will have a 248mm ring gear and 35 spline inner axle shafts but it has larger axle tubes, etc than a vintage Dana 60. All of the popular differential carriers are avaliable, including air locker, elocker, detroit locker, and eaton truetrac.

I’ve been considering the same for off-road use, mostly mud.

I’d wait for the aftermarket to catch up. No way I’d bother swapping front and rear ring and pinions to go from 3.55 to 3.73. It’s just not worth it.

So back to the Truetrac... Can anyone shed any light on how much of an improvement it might make in low traction situations like snow or mud? Anyone try it on one of our trucks?

I put one in the rear of my 06 Powerstroke. It worked great. No noise, no adverse handling, and it is always working. Frankly I wish my 16 had one in the rear axle versus the oem elocker. The rear elocker is great when you need it to be locked, but the rest of the time it’s an open differential. With the torque of the 6.7, a Trutrac in the rear axle would be very helpful. As I have said in other threads I think the perfect setup for a Super Duty is a Trutrac in the rear axle and an Eaton Elocker in the front axle. I setup my 06 this way.

It looks like Strange makes an S-Trac for the 35 spline Dana 60 also. So that’s another helical option.