I took out the shocks of the sled to be rebuilt. The fronts are fox. The rears are???? Stock most likly. They don’t look to be adjustable. Can I buy adjustable shocks and spring relatively cheap. And from where? The issue is it’s a back up sled and friends ride it, much different weight class, between each rider. Does it matter on the rear for adjustability for the different riders or just have them rebuilt. And use the old springs, how can one test the spring to se e if need a new. Or will other polaris shocks work in the rear skid? Thanks