When it comes to stroker cranks and aftermarket race rods the same length rods wiegh the same The low deck stroker crank versus the same brand and stroke length in either motor may be 2 to 3 lbs depending on the bob wieghts. My 512-518 low deck stroker pistons weighed 453 grams with no pins, rings , retainers or oil, the 527 pistons weighed 547 grams, if I'm remembering both weights correctly. the 512-518 motor has a set of CAT brand 6.800 long H beam steel rods and the 527 has a set of Manley 6.960 long H beam steel rods, the longest I could buy at that time. I'm sure the longer rod is heavier being both are steel, but both motors made almost the same power even though the 527 has more compression and camshaft I think the better heads outweighed the C.I., compression and camshaft advantage of the RB motor versus the low deck motor Lots of different ways to skin the kitty