There are still a few mods here in the SH4 download section that are for version 1.4. There is Real Fleet Boat 1.4, and at least one optics mod (ClayP's I believe); also Poul's Sound Mod works with 1.4. But, most modders work with the most recent game version, so the latest, greatest mods will be designed to be compatible with 1.5, and the older 1.4 mods will no longer be updated. But they are there. Just browse the download section, and you'll find 'em.
Good luck!