First Truck Set up.

Buy the one you want or you won`t be happy.My advice would be not to buy one at all.As for specs-the overdrive ratios aren`t that different,most are a .73 or.74 to 1.Newer trucks are gearing the rears higher(lower numbers)so your rpms are lower.You could also go with tall rubber but you will lose some pulling power.
I love a cummins engine but I don`t know the peak torque of the newer ones.My company truck is a frtlnr classic with a 470 detroit,13 speed(.73 overdrive) on 22.5 low pros-97mph(before being cutback to 78)running the east coast at just over 6mpg.rear ratio 2.89..At 70mph taching 1450.

 

I think we both have about the same trans...RTLO16913A yours is probably the RTLO 18918A isn't it?

 

18918B, could be tire difference, isnt there about 2-3" difference from LP to stand ups?

 

Not real sure about the height difference but 2-3" sounds about right...4 at the most. You know whats funny? A 22.5 tall tire is the same height as a 24.5 low pro. I never really thought about till I seen it one day trying to match up tires. For some reason that one tire wouldn't fit on that 24.5 rim...

I know the letter at the end means something different in each of the trans but can't remember the difference between the A and the B

 

Haha yeah they are the same height, beats me i dont know why it wont fit on a 24.5 rim either

I dont remember what the different letters stand for either, id say the tire size makes up for it though.

 

The A ratio set is .86/.73 in top hole and B ratio set is 1.00/.85 in top hole.
I have an RTLO16613B with 2.93 rears. 6.5-7.5 consistently.

XDA3's and 5's are 2" shorter for a 275/80R24.5 verses 11R24.5

I'm gonna start looking and piecing together a complete set of 24.5's for my truck. I think they look better

 

Too bad the question wasn't what truck to by but the specs on it.

 

Just trying to help.

 

I have a buddy who is an O/O running a 379EXHD, C-15 Acert, 18 speed, 3.36 rears, 11r-24.5 rubber. When he was pulling a standard combo flatbed cross counry, his mileage was around 5.7mpg as a 475HP. after it was bumped to a 550, mileage went up to 6.1

Now, he pulls a set of trains from detriot to chicago, grossing between 140-160K on avg, and his mileage has only dropped to around 5.6, with power to spare, even with the tall tires and tall gears.