Are the shaft drive locked up in the rear so both tires always spin? i wondered if there was a difference on 4wd and 2wd models.

 

What brand and model of quad are you talking about? Most have a straight rear axle with one drive shaft driving it off of the engine whether you're in 2wd or 4wd mode. As a result, this sort of setup drives both rear tires at all times, no questions asked. I'm not sure about those with independent rear suspension (the newer Grizzlies, among a few others) but I'm pretty sure they're locked all the time. A few models (at least some older ones) have a feature that allows you to unlock the rear axle so that it acts as a differential. Very handy when you're driving in your yard so that it doesn't tear up the grass when you turn.

JC