GO 33 WD Means general Orders #33, War Department. These orders were the 'authority' by which the credits were granted.
The arrowhead, signifies an assault landing. The Good conduct Medal was earned by not getting into any major legal difficulty with the Code of Military Justice during his time in service.
According to the Depart of the Army's UNIT CITATION AND CAMPAIGN PARTICIPATION CREDIT REGISTER Pamphlet# 672-1,
--Anzio is listed separately for credit
--No separate listing for Salerno.
--North Apennines, Sicily, Rome-Arno, Naples-Foggia and Po Valley are separate campaigns. According to the Register, the 643rd received credit for Naples-Foggia, Po Valley and Rome-Arno. It also received a Meritorious Unit Commendation dated 8 June 1945.
The 39th Engineer Combat Regiment received credit for: Anzio, Naples-Foggia, North Apennines, Rome-Arno, and Sicily. It also received assault credit for Gela, Sicily. (the arrowhead.)
Hope this helps.
Theron P. Snell, Ph.D