2.64 Mdrive?

Thats where I run with same weights. If you go with the M-drive I think youd be much happier with a 3.58 ratio on the 11R24.5's. It would keep you in the powerband a lot better. You'd be right around 1425rpm @ 67mph

 

I see you've never owned or driven one.

2.64 is common now on downspeed overdrive trucks on 22.5lp.
Cruise is 1150@65mph.

I'd If you're going 24.5 , you'd be 3.08 I believe to get similar results.

I have the 2.64/iShift(Mdrive) OD setup. It isn't lacking on hills and definitely helps improve MPG. Previous truck had 3.55s on 22.5lp. The new truck is Soooo much nicer.

I admit I was very sceptical before making the plunge though.

 

That's way too much rpm on a Mack or Volvo 13L.... It's not a old cat or Cummins N14.

These trucks make Peak Tq @1050rpm , you really don't want to cruise above 1350 on your top speed range.

11R 24.5s you'd want either a 2.85 or 3.08 rear combined with a iShift/Mdrive OD trans.

.

 

To each their own I guess. Good luck to you.

 

Heavy haul or continuously in mountains, very heavy I'm sure that would be nice.... Not gonna knock that.

It's just WAY above the sweet spot on these modern motors and lots of extra wear and fuel from the high RPM.

Have a good one