https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104500/b-1b-lancer/
The B-1B is an improved variant initiated by the Reagan administration in 1981. Major changes included and additional structure to increase payload by 74,000 pounds, an improved radar and reduction of the radar cross section by an order of magnitude. The inlet was extensively modified as part of this RCS reduction, necessitating a reduction in maximum speed to Mach 1.2.
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Inventory: Active force, 62 (test, 2); ANG, 0; Reserve, 0
(Current as of September 2016)
The first production B-1 flew in October 1984, and the first B-1B was delivered to Dyess Air Force Base, Texas, in June 1985. Initial operational capability was achieved on Oct. 1, 1986. The final B-1B was delivered May 2, 1988.
An “additional” 76,000 pounds? Those numbers are staggering when compared to a B17 or B29.
Those birds can really ruin your day.