Questions about a 2006 5.7

Sorry, I should have been clearer.

You are correct that the HC never had MDS, so it uses 16 of the same lifters. The MDS motors, even the lowly 5.7, use 8 of those same lifters and 8 MDS lifter. My comment was specifically related to the non-MDS lifters and that buying "Hellcat lifters" is pointless as all of the non-MDS lifters are the same.

I think the 2015 lifter superseded the '14 down ones from the factory, but no idea what the aftermarket shows and if they break them down.
Its what I have been doing on Rockauto. check the 07 parts, then check 2012 and then 2020, from Enginetech to Ultrapower all show the same MDS lifter as a replacement, just like the rods are the same, head bolts are the same. I just figure the same people are making these lifters as any of the other brands out there, so whoever improved them did the same thing as the mopars they copied.

Its just exhausting when you supposedly learn something and then it gets "fact checked" if I may say to change the definition.