Hello muskrat,
well I really did it with the simple green stuff, cases are dark grey. I tried walnut shells, but even at 120 psi they would not touch it. I sent an e-mail out to a vapor blaster. I know they all use glass beads and thats bad, but with care in final cleaning I should be alright. And the finish you get looks nice and is easier to keep clean I guess. I will never use simple green on aluminum again, it oxidized it worse than any aluminum I have ever seen. I realize its my fault for letting it go way, way too long- but thats how life sometimes works.
I got the sprocket off with heat and a puller. Took about an hour and it broke free- thanks for that!