Low range of the NP229 is 2.62:1, not as good as the NP231's 2.72:1. Look at the NP241 or NP242 if you want a good strong alternative to the 231.
The NP231 is strong and up to most wheelin, what's your need for the upgrade?
Being selec-trac means it can be run in full-time 4wd on dry pavement with no problems.
