Try a junkyard? They might have some old slant sixes with the oil dipstick still in them. if not, try nationalmoparts.com their's are pretty expensive but they are NOS.
Likely not hitting the junkyard soon. I tried nationalmoparts.com I didn't see quite what I needed. (at least not close enough for price/shipping) I'm happy to grab a universal one. I know I have 5 quarts now. I should probably just get one from a local parts store and mark it and call it good for now.
