If DCR measures 3.7 ohms, assuming your meter is accurate at low impedances (does it display zero when you short the probes?), a 4 ohm (nominal) car speaker should be fine.
However, I don't think that a coaxial like that JBL is necessarily the right way to go. If you want it to sound original, I'd look for a higher efficiency speaker meant for full-range/low power applications. It's quite possible the amplification was designed to make the most of thatkind of speaker and it might not sound as good if you put something in that's less efficient and has different frequency range and wasn't intended for what's effectively a quasi-open baffle application.
The JBL won't hurt anything but it might not sound right either. May not be all that much of a gamble mind you, just laying out some of the application aspects to consider.
John
However, I don't think that a coaxial like that JBL is necessarily the right way to go. If you want it to sound original, I'd look for a higher efficiency speaker meant for full-range/low power applications. It's quite possible the amplification was designed to make the most of thatkind of speaker and it might not sound as good if you put something in that's less efficient and has different frequency range and wasn't intended for what's effectively a quasi-open baffle application.
The JBL won't hurt anything but it might not sound right either. May not be all that much of a gamble mind you, just laying out some of the application aspects to consider.
John