1973 Mercury 402 will crank but won't start

[goaskbudge]

My 1973 Mercury 402 (40hp) will crank but won't turn over. The problem is that I'm not getting a spark. I have replaced the starter and the solenoid w/in the past month. It ran for a while after that and then died-- hasn't started since. I've replaced the spark plugs and have checked for spark-- nothing. When I connect a ohmmeter between the coil tower and a ground (w/ the meter set on the RX100 scale) I get a 3 ohm reading. My manual says I should have a 5-6 (for Phase-Maker ignitions). Is the 3 telling me that I need a new coil? Thanks.