Speed, Gears, Transmission......

I have 98 fld same set up but with a 13 it gets 6.2-6.7 at 70mph just fyi
buy the way a 10 over has a .74 final and a 13 has a .73

 

also have a 01 classic with 3:50 and it gets worse mpg other wise the same

 

Since everyone else is doing it:

I have an 03 Columbia, DD430, 13sp, 2.93 rears. 7.3mpg ECM lifetime.

 

double over gets you .86 on the low side of the spliter .73 on the high I was just pointing out that with a .74 in a ten it would be about the same final and cheaper in the end
I love my 13s but a ten will get the job done just fine

 

man that has got to be a slug in upper gears but nice when the fuel bills due

 

One can't argue with those (mpg) numbers, however your last two gears must have cobwebs on them, or possibly your 13sp may not be overdrive, maybe direct, or even underdrive , eh?
I'm running a 13 over with 3.36, on 24.5 standard height, and feel that I'm geared WAY to tall, especially in the hills. Even if I switched to 22.5, I don't think I would be at optimum specs for my truck.

 

I believe 13th is .85 in this particular model. It actually pulls pretty good in top gear, drop it down to 12th and it's just fine. I have my cruise sat at 65 all day long and just every so often have to bump the brake to split it down one.