13 Speed: Probably a stupid question, but...

You only use 12 in a 13 if that most of the time. I only use about 9 of my 18 a good 33% of the time. Sometimes only use 5

 

Your math is a little off. You have a low or 1st gear on the low side (all the way left and down) giving you 5 gears and then 4 on the high side that can be split giving you 8 gears.... 8+5=13... LOL

Just drive it with a "H" shift pattern and you can split the upper range.

 

I like the 10 better.
I drive a 13 everyday.
10 just as good.

Rumor has it that Swift buys the 9 speeds, then converts many of them to 13s for resale value.

 

The Fuller Convertible 9 is an option from Eaton. Slightly better for training companies and ham-handed drivers as a 9-speed then easily converted to a 13 for sale.

 

The 10 speed sucks. I guess they are ok if you never go over 80,000 or climb a hill.

 

There is a super 500 mack dump we had that had 15 forward and 15 back. Rotate the knob from low direct and overdrive. All of them are there. Run backwards at 80 mph if you like.

 

I drove one of these in a Ford LT9000 Ford years ago. Took time to get use to.

 

Drove these for a few years also. Regular 2 stick Mack

 

I converted the 9 speed in the truck I bought last month to a 13. With the overlap in rpm's to speed it is MUCH easier to stay in rpm's with power when pulling hills than with the 9 speed. The cost was $500 for my magician mechanic to purchase and install the conversion kit.

The previous truck I drove had a 10 speed. It was a challenge to drive off road. The owner installed a rebuilt 13 speed and we picked up 0.25 mpg and far better performance.