Also best to figure estimated truck and trailer? loads, type of hills to climb, required trips, etc. If all short trips, 5 or 10 MPH slower probably not make too much dif. If you're on the 'dry side' and never have or want to drive to the coast, then don't need such low gears. If light loads, flat roads, can probably cruise faster, higher O D ratio.

It might be more expense to install higher R and P, if available, less flexible shift options; less expense, more work to install Brownie, more shift options-it is nice to be able to creep around steep location, large load, backing w/ a trailer that a Brownie allows.

Last edited by EdPruss; 02/20/2013 1:47 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.