Green’s Dictionary of Slang

(US drugs) a combination of Talwin and PBZ (an anti-histamine), used as a cheap substitute for heroin.

1981		D.E. Miller Bk of Jargon 339: T’s and Blues: Potent combination of Talwin and PBZ (an antihistamine), used as a cheap heroin substitute.
1982		Cincinnati Enquirer (OH) 29 Nov. 49/2: ‘T’s and B’s are still going just as strong as ever,’ said a detective in the [...] Narcotics Division.