1970 merc 7.5 coil choices?

[roonie]

engine ser.#2957779
I keep dropping spark on one cyl. once my engine warms up. Ive been told i need a coil. The coils listed for this engine are astronomically priced. Would other coils work that are physically the same. There are coils as low as $30 that look the same. thanks in advance

 

[flyingscott]

No you need coils for your ignition which is the phasemaker.
Those coils are specific and are only available from mercury who is pretty proud of them.