The answer is "maybe". Some had the wiring in place, some did not. The stock radio does support the changer but you may have to run a single cable from the head unit back to the changer. The changer gets its power from the antenna booster on the wagons. I installed our changer myself ('95 855GLT) and it was pretty easy. The instructions were acutally quite good. The standard installation location is in the rear under the floor (spare tire well) on wagons, but there was an optional mounting kit to put it upright on the LH side. That way you don't lose the storage space in the wheel well.

See if the newer style (98-00) mounting kit is listed to fit the wagon as it is much more elegant with a hinged cover and does not stick up as much in the cargo area as the original '95 version.