- IX 300 (Prinz Eugen): ex German heavy cruiser.
- IX 301 (Dithmarschen): ex German oiler, see AO 110 (Conecuh)
- IX 304 (Atlanta): ex CL 104, 1964
- IX 308 (New Bedford): see AKL 17
- IX 309 (Monob One, ex YW 87): see YAG 61
- IX 310: Sonar systems measuring barge on Lake Seneca, NY, mentioned as "unclassified" 28 Dec 1970, designated 1 Apr 1971
- IX 311 (Benewah): see APB 35, 1971
- IX 502-504 (Mercer, Nueces, Echols): see APB 39, 40, 37, 1975-6
- IX 505-506: Ex service craft YTM 759 (ex Army LT 2077), 1976, and YFU 82, 1978
- IX 507 (Gen Hugh J Gaffey): see AP 121
- IX 508-509: Ex service craft LCU 1618 and Underwater Demolition Barge No.1, 1979
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