I don't recall what the exact difference is, but I just read somewhere a day or two ago that LA and Magnum pistons are different. I'd probably stick with the LAs.

1972 Dodge Charger - F7, Rallye pkg, 340, A833
2007 Dodge Charger R/T R&T - 12sec daily beater
1999 Dodge Dakota R/T - M1, cam, heads, T56 swap
1997 Dodge Dakota - 318, NV3500, 3.92 Sure Grip