The ONE advantage you have over your late model over us with "older" ones is that you do not have what we call a "full current" ammeter. This means the bulkhead connector is under less strain
Also look for and check other fuse links. These always have an obvious bulge "for no reason" and or a molded tag hanging out to the side.
Checking fuses.......don't just look at them. Some of the fuses are hot all the time, some are hot only when the key is in "run" or "accessory." And one fuse, the INST fuse, is only hot when the light switch is "on" but ignore that one for now
To check fuses, get power TO them and check at the fuse with a light/ meter. Then apply a load such as tail lights heater whatever is on that fuse, and make certain you have power at both ends of the fuse clips
For these tests, a test lamp is often better/ easier than a meter