Can't say I ever saw any Grundig radios in Ford cars?, and of course Grundig went bust a fair few years ago now. At one time Ford used radios laballed Ford and made in Brazil, never had a clue who the manufacturer was though.yes It is an. original radio but on my experience fixing problem , FORD Europe used to install Grundig onto cars so one occasion requested to Grundig and they gave me schematics and IC PLL . Sanyo too. but I can no find any web for Delco electronics ...maybe it was bought .
On a car radio? they are pretty universally 4 ohms, so as to gat the maximum power (about 4W, or 16W for bridged)."It" doesn;t have a model #. Those schematics of yesteryear were sold in books like Ryder's manuals. Check samsphotofact first.
Some had high impeadance speaker outputs like 20-30 or 40ohms.