I'll have to agree with Brent. I have these cut-off wheels for the angle grinder. It cut through 1/4" steel like butter. Works like a charm.

If you are going to go with a sawsall, get a carbide blade and keep it oiled when cutting through thick metal. I used them to cut my Camber bolt during the upper control arm install.
Those were grade 8 (or metric grade 9?) and a bitch to cut, but the carbide blade worked pretty well.

Good luck.