You are asking for a BIG answer to list EVERY GEARING equipped with the 3-in RFG mounts (most with two twin and two single mounts). No 3.5-in guns however. All GEARINGS except for (depending on how you count DD-849) 30-31 units were upgraded to 3-in RFG mounts. This includes the DDE and DDR variants.
First off there were 98 GEARING's, if you include the variants like USS TIMMERMAN (DD-828), which never had the 3-in RFG mounts installed.
USS RICHARD E. KRAUS (DD-849) was the first destroyer to have the twin 3-in RFG mount installed. She carried only one twin and the rest of her AA armament were 40-mm guns until she was FRAM'd.
Of the seventeen DDE GEARING's, only two units had twin 3-in RFG mounts (no singles, DDE-719 and DDE-824. Two GEARING DDE's were completed with twin 3-in RFG mounts as their main armament which were eventually replaced with the 3-in/70cal guns, DDE-825 and DDE-826.
All 36 of the DDRs were upgraded with the 3-in RFG mounts, in at least three different configurations during the 1950s.
That leaves the 43 GEARINGS that remained as "Fleet Destroyers" during the 1950's. Eleven units never were upgraded with the twin and single 3-in RFG mounts, DD-710, 712 (got two twin 3-in RFG mounts when modified as a DDG), 782, 783, 785, 787, 836, 851, 864, 869, and 886. That leaves 32 GEARING Fleet Destroyers that were upgraded with 3-in RFG mounts. The first units upgraded had the two twin 3-in RFG mounts staggered on the aft deckhouse in locations where two of the quad 40-mm mounts were located (and two single mounts on bridge wings), DD-716, 717, 718, 788, 789, 790, 821, 822, 823, 826, 839, 840, 846, 850, 852, 853, 865, 868, and 872. The remaining units had the revised configuration with the two twin 3-in RFG mounts on the centerline, DD-763, 786, 841, 843, 844, 845, 862, 866, 867, 884, 885, 887, and 890.
Of these all had tripod foremasts with the SPS-6 radar antenna (some were connected to SR-6 and some to SPS-6 radars), except for DD-788, 789, 821, and 865 had pole foremast when upgraded with the 3-in RFG mounts, but were subsequently modified with tripod foremasts, and DD-826, 839, 867, 872, 885, and 890 retained pole foremasts until FRAM'ing.
Select which unit you which to model from this matrix. (I made a Excel spreadsheet to keep all this STRAIGHT)