from what i know the 4/6/8 motor was only used in 81 in all caddys that had the 368 power plant in 82 the commercial chassis (hearse got the carbed 368 while limos got the 4/6/8 368 until 85. I have an 84 superior hearse with the carbed 368. a dead give away is the valve covers have a tall deck in the center that would indicate a 4/6/8 motor. also a mechanical fuel pump on the drivers side just under the powersteering pump would indicate the carbed 368. Just wanted to mention those since you said your car is a hearse and as far as i know all 84s should have the carbed motor, but then again hearses are optioned very unique and anything could be possible.