jazzmandolin

Which years factory air conditioning system are direct fit into a 86 pickup. Someone has told me that they changed in 87 or 88? I thought they were all the same from say 85 to 88? Found 86 ac system at the local pick and save but the motor has been removed and the bracket idler is gone rest of the ac system is intact though. About to head out to pull it. When I start searching for the bracket idler I want to make sure I will be searching for the correct one! Thanks