4013587 is the latest part number. The other one is the original on 2010s I know. I just replaced the original on a 2010 Dragon and got the 3587.
It would appear that both have an ECU isolation circuit in them now though. I spoke with the mechanic at Tri-City and he mentioned that they don't see bad regulators killing ECUs any more. And in my case it didn't kill the ECU either.
So if you want the latest from Polaris get the 3587, but the 2476 works too.