Gen VI 454 Questions (96-00 Vortec)

[RustyBolts]

I was looking through parts catalogs and such today and noticed something a bit odd.
For all '95 and older engines, the distributor is the same part number for both Big and Small-Block Engines.
For the '96 to '00/'01 engines, there's a different part number for the two.
Does anybody here know what the difference is?

 

[Mike]

Not 100% positive if this is the reason for different part numbers but in 96 the Vortec 7400 was refitted with a hydraulic roller cam.

 

[RustyBolts]

HMMM. I don't think that's it because the small blocks got a roller cam in '87.
If it was the case then I would think the '87 to '95 BIG BLOCKS would have a different part number, and not the '96 and up
My thinking was maybe they changed it to fit around the MPFI setup on the 7.4, but then again, i have no idea.

 

[RustyBolts]

One more question. Which was first, Oval port, or Rectangular port heads?