For 1977, the Eldorado received a new grille with a finer crosshatch pattern. The convertible was canceled (although Custom Coach of Lima, Ohio took a few brand-new 1977 and 1978 Eldorados into their coachbuilder facilities and converted them into coach convertibles using salvaged parts from 1971-76 Eldorados; Cadillac did not produce convertibles after 1976). The 8.2L V8 of 1970-76 gave way to a new 7L V8 with 180 bhp (134 kW). Also in 1977, all E-body cars were exclusively front-wheel drive for the first time, when Buick removed the Riviera from that platform during a two-year hiatus (after which it also switched to front-wheel drive in 1979). Minor changes followed in 1978.
The 1978 Cadillac Eldorado was the only American luxury car in its class (or any car class) to be offered with Power Sliding T-Tops that folded neatly inside the center-front roof. In this regard, only seven 1978 Cadillac Eldorados were known to have been produced with Power Sliding T-Tops customized and manufactured by American Sunroof Company under the direction of General Motor’s Cadillac Motor Division. There are seven known 1978 Cadillac Eldorados with Power Sliding T-Tops remaining: One (1) Black Eldorado Cabriolet; One (1) Carmine Red Eldorado Cabriolet; One (1) Cotillion White Eldorado Cabriolet; One (1) Colonial Yellow Eldorado Custom Biarritz; Two (2) Cotillion White Eldorado Custom Biarritz and One (1) Two-Tone Arizona Beige/Demitasse Brown Eldorado Custom Biarritz Classic.
Source: Wikipedia, 2012