i think the sq axle models had the 4 speed trans with hi/lo, no multi-power. That is the model that you want.
the others had 3 speed trans with or with/out multi power.
some love multi power others not so much,
if M/P is out or not working, then you have no motor braking in either low or high range or maybe none, i just do not remember for sure.
many folks would not let kids drive these tractors as they can be squirrly with no engine braking.
brakes must be in class one condition and with oil leaking at the axle, that brake probably has oil soaked brake linings.
be sure to ask others before you buy the tractor, i drove them but never owned one,
However, i liked the m/p shift, the tractors i drove, most of them, this fuction worked.