What you should be seeing on the back of the alternator is a fairly large threaded terminal post with a "B+" imprinted into the alt body beside it (but not all units have that imprinting). With the alternator in its normal mounting attitude, that post is at about 1:00 to 2:00 o'clock when viewed from the rear. If you look closely, you'll see that it's insulated from the body. That's where the large Red wire attaches.

A smaller terminal nearby, frequently sporting a male 1/4" spade connector, and perhaps labelled "D+" is where the small red wire attaches.

...and make sure the ring terminals on the ends of the Blue grounding wire are clean and firmly attached to the wire, then firmly connected to the alt. case and the engine block. ALL the charging current returns to the negative circuit of the alternator through that bit of wire.
--
Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and a few old motorcycles)