The year 1979 saw the addition of a new Delta 88 Royale Brougham series added to the line, which included plush "pillowed" seat trim similar to the Ninety-Eight. All models again received revised grilles and other minor changes. It was the last year for the 403 as federal fuel-economy mandates spelled the end of larger engines in order to meet those requirements.
As in previous years, base Delta 88 and Royale models differed mainly in exterior and interior trim. Base Deltas had a full bench seat available in cloth-and-vinyl or all-vinyl upholstery, while Royales had a notchback bench seat with armrest or optional 60/40 notchback bench, also available in cloth-and-vinyl or all-vinyl trim. All 88s featured an all-new instrument panel with a horizontal sweep speedometer and heater/air conditioning controls moved to the center of the dash above the radio from the left side of the dash, and continued with the "Message Center" bank of warning lights. The new dash was highlighted with woodgrain trim. The dimmer switch moved from the floor to the turn-signal lever.
The 1969 88 series dropped the Delmont name, leaving the Delta 88 as the base model of the series. The Royale trim appeared on a top-line Holiday coupe and came standard with a more luxurious interior featuring a notchback vinyl upholstered bench seat with armrest or Strato bucket seats with optional center console. For safety, a ceiling mounted shoulder belt was offered in the front seats for both the driver and right passenger. This arrangement provided five belt buckles in the front bench seat. The standard engine in the base Delta 88 was a 350 cubic-inch 9.0 to 1 low compression ratio Rocket V8 with a Rochester two-barrel carburetor that was rated at 250 hp (186 kW) at 4,600 rpm and 355 lb·ft (481 N·m) of torque ran on leaded regular 94 RON gasoline. Standard on the Delta 88 Custom and Royale models and optional on the base series was a low compression two-barrel version of the 455 cubic-inch Rocket V8 rated at 310 hp (231 kW) designed to use regular fuel. Optional on all Delta 88s was the four-barrel Ultra High Compression 455 cubic-inch Super Rocket V8 rated at 365 hp (272 kW). Top option was the 390 hp (291 kW) version of the four-barrel 455 V8 designed to run on 98 RON octane fuel available in all Delta 88 models as the W-33 option.