I just realized that this says "Redhawk Question"...
There were only about 5,000 Redhawks made in .357mag, so they ain't easy to find. Then, on top of the rarity, if you want a convertible Redhawk, as mentioned, you have to get a spare cylinder and crane assembly, meaning you have to buy ANOTHER .357mag Redhawk. It's largely cost prohibitive to do so, because you have to buy two rare .357mag Redhawks, then you have to be willing to send 80% of a perfectly good Redhawk to the scrap heap and have the spare cylinder assembly machined to 9mm to have a convertible Redhawk, AND then you have a really ugly 357mag chamber in front of a 9mm chamber, and have to take the gun apart (quick, but not mindless) to change cartridges...
How do I know all of this? I have a Convertible Redhawk - but it's not a 9mm/357mag...