hello

have a 99 c3500 crew cab its been lowered but im not sure by how much, my ctc on rear shocks is about 15 1/2 static. have no idea what standard ride hieghth is. my qustion is can someone help me with info and or brand of shock to use. im sure the standards were left on and there is not enough stroke in the shock for a 1ton. no one around this area seems to know. thanks