The Bombardier NEV was only produced from 1997 to 1999 and used a 72v shunt wound motor with a 300 amp controller.
Any controller that can accommodate 72v with a minimum of 300 amps will work.
Curtis makes a model 1244-64 controller that is good to 80v with a 400 amp rating.
Alltrax doesn't list one but I'm sure they make them and Logisystems probably make one as well.
The batteries are a b*tch to change and they only have front brakes.
Misc parts are scarce but some may be located here:
http://www.peacockltd.com/miscpage_002.asp
They're a cool looking little cart and still a couple of them running around in my neighborhood.
They looked like this:
