To give a quick summary, yes, there are good parts only found on the 442 and
H/O that arent found on the regular Cutlass's.
First off for the 84
H/O and all the 442's are the 8.5 rear axle. Stonger than the 7.5. Very desirable piece.
The 2004r transmission's are all the same between all the Cutlass's except for the valve body. They are a little bit different for the hi performance cars, better shifting more positive shifts.
Chrome SSIII wheels 15x7 that only came on the
H/O's and 442s. All other SSII wheels on Cutlass's were 14 inch wheels.
307's for the vin9 cars were higher output engines vs. the stock vin Y 307 engines. Not a big difference, but there is a difference.
Anything else you want to know about the links above should cover it.
There are many more differences, but they are minor.