Which 9 speeds can be converted to 13’s?

Wondering what 9 speeds can or cannot be converted to 13 speeds. Is the RTLOC’s the only one that can be converted? RTLO(C), for “convertible”?

 

Most all Rt,Rto, 9 speeds can be converted. But you need to know what version your building. Short end of this, any capable trans shop can help source the parts. I do think I would disassemble and verify any used trans before ordering parts. Who know what someone could have used on last rebuild.

The C, or convertible trans was a marketing gimmic. It was a 13 speed without air valve. Big sale to fleets like Werner. They would add air valve, change shifter knob, and sell used truck to a OO with a 13 speed.


I have no knowledge to add on Rockwell, or Spicer.

 

H&W did the same thing, trucks had a 13 spd transmission with a 9 spd shift knob. Most of us carried a 13 spd knob in our clothes bag, change it across the state line and then change it back end of the week before getting to the yard…..

 

I like a 13 and they’re getting hard to find in my area. Which OD 9 speed would be the best to make a 13 into, for a 450-600hp truck?

 

Less than built 13 speeds. Your TQ is more important than HP. Most big TQ motors never got a 9. Unless someone was the cheapest SOB around. Your gonna get a 9, and build it to your TQ for your application. Big power and going fast had a cost, how fast can you afford?