Melling vs Stock push rods and rocker arms

[Jowers]

So I'm taking my sweet time putting new heads on my 4.0 OHV. Figured why not do a little not-so-scientific comparison of the factory (150k miles) rocker arms/push rods to the new Melling replacements I ordered from Rock Auto. Couple things I noted. First, the Chinese Melling rocker arms are about 10% heavier. Lower carbon content/ softer/ less durable? Second, oil passages were a little larger on the Mellings. Third, Melling push rods are significantly more voluminous. Hollow tube vs solid from the factory? Disclaimer: I'm not an expert or an engine builder per say. Just throwing this content on here in case anyone is curious.