[DaJudge]

Good info on both posts Bobcat. The official stance from the factory and publications are that no 421's or 428's were factory installed. Special dealers like Royal etc. installed these engines for customers as an upgrade or upcharge. Unless it can be substantially documented as such you would have to agree that a GTO with this conversion would be an incorrect restoration. I disagree with your expanation of non-matching vin numbers in cars and that if one was off the whole line would suffer. One engine may be outfitted for A/C and power steering etc for a vehicle. If the next vehicle in line had or was missing these options the accessory mounting brackets are different as are balancer pulleys and water pump pulleys. Pictures that I have seen show all accessories on the engine before installation into the chassis. The workers would create bigger problems for themselves and really slow down production if they followed your explanation. My friend owned a 70 RA III Judge that was an original paint car and never touched a real survivor by the strictest definition of the term. It had three build sheets and only three owners. The car was ordered as a RA IV but came through as a III. The last digit was a 5 like a IV block should be but was coded a RA III WS block. The VIN on the block and trans was one digit off from the VIN plate. When the VIN number on the block and trans was submitted to PHS it was run through every possible vehicle series . The VIN on the block and trans came back "does not exist" from PHS. The engine and trans never left the engine bay on this car ever. This is an example of a factory mistake that from what I am told happened more than once.