DRG FLT IN AN AREA OF IFR CONDITIONS & RAIN SHOWERS, THE PLT REQD & RECD CLNC TO DSCND FROM 9000' TO 7000'. LATER, HE RECD CLNC FOR FURTHER DSCNT TO 5000'. AFTER A FREQ CHG AT 2237 EST, THE PLT INQUIRED ABOUT RADAR INDCNS OF ADVERSE WXAHEAD. THE CTLR ADZD THAT THERE WAS SOME PRECIP IN THE AREA (NR GAINESVILLE) BUT THAT HIS ROUTE OF FLT LOOKED 'PRETTY GOOD.' AS THE ACFT CONTD, ITS ALT VARIED FM 4900' TO 5100' (AS INDCD BY THE MODE C TRANPONDER RETURN). AT 2242:53, THE MODE C REPLY INDCD 5100'; 12 SEC LATER, IT INDCD 5600'; AFTER ANOTHER 12 SEC, THE ALT REPLY HAD DECREASED TO 4300'; THENRADAR & RADIO CONTACT WERE LOST. AN AIR SEARCH WAS DELAYED DUE TO STRONG WIND & RAIN. THE WRECKAGE WAS FND ON 1/1/87 IN THE AREA WHERE RADAR CONTACT WAS LOST. THERE WAS EVIDENCE OF AN IN-FLT BREAK-UP. THE OUTBOARD PORTIONS OF THE HORIZONTALSTABILIZERS & WINGS HAD SEPD IN FLT. AN EXAM REVEALED THEY HAD SEPD DOWNWARD FM OVERLOAD FAILURE. PERSONS NR THE CRASH SITE RPRTD HVY RAIN & WIND WITH SOME LIGHTNING & THUNDER AT THE TIME OF THE ACDNT.