I recall reading where a B-47 on a recon mission was intercepted by Migs and, running low on fuel, was calling for help. A KC-97 pilot heard the B-47's calls and asked the tower at the base if they heard them. They had not received the signals, so he took off and headed for the B-47. I'll have to see if I can figure out where I read that.
A friend of mine was stationed in Germany right after the war and vectored two P-80's to intercept a target that had been violating West German airspace at night and proved to be too fast for P-51's and P-47's.