only dangerous if you are underneath em when you take the bolts out!!!
Beware of pro-comp stuff. Fitted 3.5" lift to customer's XJ recently - Bottom leafs on rear springs splay out when going off road. All bolts f'ing tight. Explorer have no answers for this as yet. :? I suspect I will have to fabricate some kind of 'U' braket to sort this. Diesel springs are tough as old boots and will cure the 4.0L XJ sagging syndrome. Unless You are planning to Lift your truck this is the way to go. New U bolts/nuts are a must though!