I know there are a lot of threads on this, and i've read them all (i think!), but there's one question (edit: okay, 2) nagging at me that i seem to be unable to find an answer to and i hope somebody can explain ...

What's the difference, besides colour, between a black and silver top? Also, i've noticed some of these cam covers have their oil caps right at what would be the back of the engine bay in a sierra, whereas other have them closer to the pulleys. Why's that? Closer to the front would obviously make filling easier, so: Is it important?

I reckon i can complete the conversion, and i'm sure it'll be facinating, but having never owned a zetec engine i'd prefer to know what's what. Whatever - something's gotta be done, i don't think i can scrape the old CVH through anoither emissions test.

Can someone knowledgable help me out?

Much thanks in advance.