I curently run a Cat H-63 hammer ( 500 ftlbs ) on my Cat 303.5. I am trading for the Cat 303.5C CR which is about 1000 lb heavier machine. I want to deal hammers as well but my salesman says that the hammer replacement would be a new model H-55D hammer the same foot lbs but 1/3 less tool weight. I am a little concerned that the replacement hammer will not be as effective because of its smaller size. ( although they say it is the same foot lbs.) What do you guys run for hammers on your 4.5 ton machines? I look at different sites and see 750 foot lb hammers at the same physical weight....confussed!