What is the correct oil filler tube cap for the '68 400? Is it the one that has the raised pieces of metal on the top to grab is (like a vintage gas cap), or should it be a smooth, plain top?

 

http://cgi.ebay.com/ebaymotors/NOS-6...spagenameZWDVW

 

OK, that's what I thought. Except mine is a far cry from chrome. And I'm not paying $125 at the moment to buy a NOS one. haha.

 

X2. Isn't it amazing what some people ??value/price?? NOS parts at? As Joe P is very fond of reminding us, just because it's priced that way doesn't mean it's worth it. I love to get ahold of NOS parts and will buy them if they are priced "reasonably" or I've "just gotta have it". You will probably find this thing still listed at the same price for the next 10 years until someone who has 40 gajillion dollars "snaps up a good bargain". LOL
Most of us don't have this kind of money to throw around. Bet you could take your original and restore it to look like this for less than 40 bucks.

 

I don't believe that all the originals were chrome...The style is correct but mine wasn't chrome either

 

Correct. They were engine color, at least for the most part. I don't know if there were any special Olds engines that got that style of cap in chrome. '66-'67 W-30s had chrome caps, but they were the older top hat style.
I just used that to show the style (shape) of the cap, as that was the original question.

 

I should have one or 2 of those laying around here. Let me know if you would like one, and I'll look.

 

That E-bay cap is the wrong one...the correct cap is an FC-60, it has a flattened centre rivet? with four dimples on the rivet ...stamped in a circle...ENGINE OIL FILL---AC-FC60...that chromey thing is correct for my '77 Vette