10 or 13 speed?

Depends on the hauling. I prefer more gears over less.

 

Generally yes - 9th and 12th will be 1:1, direct drive, and 10th in a 10speed and 13 in a 13 speed will be 'OD' - but the ratio of overdrive may be different.

I'm with @lots of character - I prefer more gears, I split 12th/13th a lot, run 55 mph zones in 12th, just depends on what you need.

 

Unless you mainly pull light loads on flat ground. Get the 13. If you don't, you will wish you had.

 

Get the 13, you'll never desire a 10 again....

 

13 all the way if it is for you to drive. If it is for a driver I would need to think twice as a 10 speed is pretty hard to tear up.

 

Depends on the transmission. There are direct drive transmissions, and overdrive transmissions with variable ratios. The transmission nomenclature can be looked up to determine the final drive ratio of the transmission. Personally, I'd opt for the 13... less gap between gears.

 

I agree with everyone on the 13 over the 10. No one has answered your initial specific question on final ratio, but without knowing the model #'s of the transmissions, we can't. You have to know them, and then you can either look up the ratios yourself, or we can help you. The final ratio of your top gear plays a big part in the personality of your truck as you drive it at cruising speed. Case in point, I bought a brand new truck in 1980, it had a 13 speed with a .86 od ratio (single overdrive). But, it had 10:00-20:00 tires (comparable to todays 11R-22.5 I believe) and a 4.56 final rear end ratio. It was great in the bush and in the mud, but it was a dog on the highway. I always seemed to be pushing it to try and get 60 mph out of it. Looking back now I would have been better off with 4.10 or 3.90 ratio in the rear end. 18 speeds (with the double o/d .73) hadn't been invented yet.

 

That's what the auxiliary brownies were for @04 LowMax