What kind of snow mobile do you have? Until a few years ago, most snowmobiles didn't come with reverse, but for most now you can get an after market kit to add electronic reverse (which is better than mechanical reverse anyway).
My friend has a 2003 ProX that didn't come with electronic reverse, but he bought the Polaris option kit. He paid about $500 because you need three pieces:
CDI
wiring harness
button to activate electronic reverse
For Polarius: http://www.purepolaris.com/Detail.aspx?ItemID=2874616
It's a little mechanical and rewiring, but he's not really mechanically inclined and was able to do this without any problems.





