"The biggest change to the airplane came in 1984, when a 300-HP Continental IO-550 replaced the IO-520. There was an all-new (and very well laid out) instrument panel. Gone was the trademark Bonanza "throwover" control wheel with its massive central column in favor of a pair of ordinary control yokes."
The Baron and Bonanza changed to a more conventional flap/gear handle in 1984 also.