[vettestr]

I will defer to the engine guru's as to any benefits of iron or aluminum since each is a Dart aftermarket piece. Aftermarket alum over a stock iron block would be a bigger spread. I would guess the alum block to be slightly stronger with benefit of technology and greater manufacture-ability of the aluminum alloy availabilities. Weight savings are not as large as many would think because alum. must be thicker than iron for same strengths.

If you damage an alum. piece it can be repaired much easier than cast iron and made good as new. Just hard to beat the wow factor with lighter weight and repair-ability just added benefits.