Buy a set of comp, scorpion, harland sharp....something not "unknown". 

I would contact some of the bigger players and ask the diameter of the trunions, then buy the biggest ones.  You don't need stainless....they're covered in oil, there a much better materials out there when corrosion resistance is not an issue....which it isn't.

The rocker that busted is aluminum roller, May not need stainless, but want it.
never had a failure with stock steel rockers, in countless motors, but I dont want to go back to stamped steel, either. already have some decent upgrades in the valve train already, thinking maybe aluminum's not for me.
Teague Marine-prolly out of my broke-azz-jet-boater budget & motor only turns 4900
found scorpions @ summit, still got some research to do

Daniel

Have an unknown set of aluminum roller rockers, and one broke in half
Been thinking of going stainless steel, anything to stay away from?

looking at these
http://www.prwonlinestore.com/zdstainlesssteelrockerarms37.aspx

I might be mis-interpreting your post, but my interpretation of "unknown" is essentially equal to "cheap."  And that puzzles me because based on that interpretation, you broke a cheapo rocker arm and then ask if you can replace them with another brand of cheapo rocker arm.

If you instead buy a quality, top-name brand of rocker arms that have proven themselves on countless engine builds, and set them up with proper valve train geometry, then you ought not have any problems for the typical lifespan of a set of roller rockers.

LO