A 1946-48 Dodge used a MAW-4041 and a 1942 Dodge used a MAW-4041. If the MAW series use the same ones, then it's NAPA Echlin ECH A505.
UPDATE - I just checked the 1995 Edition of the KFOCI Handbook and it has a parts cross-ref in the back. It does indeed list the ECH A505 as the correct starter brush set for the 1947-51 Frazer. NAPA has the set for $7.99 on NAPA Online or go to your local store and they can get it.