Oil Leak?

I asked a similar question a couple weeks ago but now I am really not sure so here goes

I have a warmed over 360 in my dart with a RPM Air Gap intake and an automatic tranny. I have a oil leak that I can't really find. When cruising around town it is not noticable at stoplights, etc, but after cruising on the highway I get little wiffs of oil and I notice that my exhaust and tranny have oil on them. I check the oil and I am losing some but it only amounts to a 1/2 cup or less in a 50 mile trip but the mess is more than I want to deal with. Opinions on where it is coming from would be appreciated.

Thanks

Mike