99 topkick top speed

[kcstreetracer]

I have a 99 c8500 single axle dump truck.  Cat 3126 with allison automatic.  My top speed is 50mph. Is there speed limiters or can it be adjusted? Anything I can do without changing gears?

 

Has low pro 22 5s on it, can I go to a taller 24.5 and get any significant increases? I'd like to be able to run at least 60 on the highway.  

[tommenzel]

Good afternoon KC ,  I have a 2002 GMC  T-7500  cabover , 3126 with  Allison 2000 series  ( no parking pawl type )   I bought it new ,  it was geared waaaaay to deep for my work .  I changed tire dia ,  however not enough change in road speed for my liking , changed to 2 speed rear end  which provided deep grunt off road & in gravel pits ,  And empty top speed only of use in the Western states .  I don't like typing . Tom (208) 750-8081