The Republic F-84G was not only the most widely produced version of the F-84, but was also the first single-seat fighter that was nuclear-capable, able to carry and deliver via LABS the Mark 7 nuclear bomb which itself was the first tactical nuclear weapon for US forces. The Mark 7 had a variable yield. So that the F-84G could deliver its weapon deep into enemy territory, it also became the first single-seat fighter to have a slipway refueling receptacle on the upper port wing to take fuel from boom equipped KB-29s or KC-97s.
Source: International Air Power Review, Volume 24. "Warplane Classic: Republic F-84" by David Willis, p137-138.