Back when AM was the primary radio band, stations kept their facilities in better shape, so Class IVs probably got out 60-70 miles on a car radio unless there was a cochannel or adjacent. You could get a mixture of WMBN and WMTE on the car radio as I recall. And I think WKLA came in on the car radio also, and possibly WATT. WTIQ may have come in over the lake, as I know it shows up alone during critical hours to this day. I remember hearing "Wide Trackin'" on a 1420 station near sunset near Arcadia. I assumed it was WAMM or thought I heard an ID since that was Terry Knight's hometown, and may have been a DJ briefly at WAMM, but looking at ARSA playlists and the patterns, it could have been WIMS or WHK also. Was WPLY 1420 Top 40 and do you remember hearing it in Michigan? Another possibility. We have a large contingent of people who vacationed in that area in those days. All the stations playing "Summer Songs" this weekend really brings back those memories! Rich, David, HGR1290, and others may remember some other details of what came in where.
One summer night in the late 1960s, I had no problem pulling in WKNR 1310, WILS 1320, and WTRX 1330 in that same location on a fairly sensitive transistor radio for that time.
Benzie County and Leelanau County never had any AM stations to my knowledge.