Here's a link to all the SB rockers that SM sells:
[URL][URL]https://www.speedmaster79...?enginemake=Chrysler&family=Mopar-Small-Block[/URL][/URL]
The first set, 1.5 with steel hold downs, is also sold by PRW. I have a set of these from SM, and besides needing to be washed, they were really nice. Bronze bushings, decent machine work. (both links below)
[URL][URL]https://www.speedmaster79...Stainless-Steel-Roller-Rocker-Arms-W-Hardware[/URL][/URL]
[URL][URL]https://store.prw-usa.com/3231811-small-block-mopar-273-360-1-5-ratio-complete-kit/[/URL][/URL]
The other two sets, 1.5/1.6 with aluminum hold downs, those seem to be sold only by SM. They use iron bushings, were full of machine chips/junk, the threads on the arms/adjusters/nuts were iffy and the adjusters even had the oil holes drilled wrong. (links below)
[URL][URL]https://www.speedmaster79...0-Ratio-Stainless-Steel-Roller-Rocker-Arm-Set[/URL][/URL]
[URL][URL]https://www.speedmaster79...0-Ratio-Stainless-Steel-Roller-Rocker-Arm-Set[/URL][/URL]
They're all made from the same forging. But my guess is that, like a lot of china made parts, the range of quality runs from junk to ok. The first set seems to be made for PRW and then SM picks them up from the same factory, which also makes the iron bushed ones specifically for SM, but with much lower QC.