You need a rectifier for the older sleds, even the ZX chassis. Bombardier doesn't sell a kit, but you can get one from Polaris and cut the wires. I picked one up on ebay, but haven't installed it yet. A new one is about $50 US, about $75 or $80 in Canada. In the GPS forum you may be able to find a diagram on how to make one with Radio Shack parts