IMHO, that plastic dial would never be authentic to that vintage of phone.
It is true that all new 1939-1941 color 302s with metal housings -- in the "metallic" colors such as oxidized silver -- had 5H dials with matching (painted metal) finger wheels. (Metal 302s painted old rose, Pekin red etc. had 5J dials with unpainted stainless steel fingerwheels.) (Thermoplastic color phones, introduced in 1941, had 5J dials with clear fingerwheels.) However, the production of all new color 302s was discontinued by August, 1942 (BSP WR-C30.011 Issue1, 8-5-42). New color phone production resumed only in 1949 (BLR v27, p. 43, Jan. 49).
Metallic color (old brass, statuary bronze, oxidized silver, dark gold) 302s from 1949 or later were issued from the WE repair shops only, not from the WE factory. As Doug pointed out in reply #7, this phone has a 1951 base. It also has the white stamp on the base pan as was done in the repair shops. Note that in the 1950s ad, all the color 302s had 5J (or 4J) dials with white cases and Lucite finger wheels by that time.
There have been no new metal 302s reported later than 1946. This set was apparently assembled in the repair shop in 1951 or later, so the clear fingerwheel, on a 4J or 5J dial, is correct.
