A complete reworking of the front header and bumper highlighted the 1977 Grand Prix, which was the final year for the 1973-vintage bodyshell that was set to be replaced by a downsized GP for 1978.
 The parking lamps were now positioned between the quad headlamps (same setup as a 1967 or 1968 Oldsmobile Cutlass), and the previous year's 'waterfall' grille was replaced by a narrower one that extended into the lower portion of the bumper.
 Behind the bumper were new reinforcements (mounting panels) made from aluminum rather than steel to reduce weight.
 In back the taillights were simplified to eliminate the weighty pot metal bezels that created the horizontal stripe effect in 1976.
 The same three models (J, LJ and SJ) were carried over with engine revisions.
The base Model J got Pontiac's new 135 hp (101 kW) 301 cu in (4.9 L) V8 as standard equipment, which was much too small and underpowered to propel a 4,000-pound car.
Optional engines included a 160 hp (119 kW) 350 cu in (5.7 L) V8 or 180 hp (130 kW) 400 cu in (6.6 L); those two engines standard on the LJ and SJ models, respectively.
 The original thinking on the 301 CID engine was that the weight savings from using a significantly lighter engine would cancel out the horsepower loss from the smaller displacement.
 This turned out to be a major miscalculation and 301 equipped cars became much less desirable among Grand Prix enthusiasts and collectors in later years.
 The 301 also had a knocking (pre-ignition) problem that was later determined to be caused by the shape of the combustion chamber.

Each of those engines were Pontiac-built units as in previous years, but offered in 49 of the 50 states.
Because Pontiac's own V8 engines could not meet the more stringent California emission standards set for 1977, all Grand Prixs (and other Pontiac models) sold in California were powered by Oldsmobile-built engines including Lansing's 350 cu in (5.7 L) "Rocket V8" for J and LJ, and the 403 cu in (6.6 L) Rocket V8 standard on the SJ and optional on the other two GPs in California.
Due to a shortage of Olds 350 engines resulting from record sales of Cutlasses and reduced production of that engine due to a plant conversion to build a Diesel V8 beginning in 1978, a few 1977 Grand Prixs destined for California reportedly came off the line with a Chevrolet-built 350 cu in (5.7 L) V8.

Grand Prix sales increased to an all-time high of over 270,000 units for 1977, the last year for this bodystyle, despite competition from a newly downsized and lower-priced Ford Thunderbird introduced this year and a restyled Mercury Cougar XR-7 whose bodyshell switched to the T-Bird this year from the discontinued Ford Torino/Mercury Montego.
A complete reworking of the front header and bumper highlighted the 1977 Grand Prix, which was the final year for the 1973-vintage bodyshell that was set to be replaced by a downsized GP for 1978.  The parking lamps were now positioned between the quad headlamps (same setup as a 1967 or 1968 Oldsmobile Cutlass), and the previous year's 'waterfall' grille was replaced by a narrower one that extended into the lower portion of the bumper.  Behind the bumper were new reinforcements (mounting panels) made from aluminum rather than steel to reduce weight.  In back the taillights were simplified to eliminate the weighty pot metal bezels that created the horizontal stripe effect in 1976.  The same three models (J, LJ and SJ) were carried over with engine revisions. The base Model J got Pontiac's new 135 hp (101 kW) 301 cu in (4.9 L) V8 as standard equipment, which was much too small and underpowered to propel a 4,000-pound car. Optional engines included a 160 hp (119 kW) 350 cu in (5.7 L) V8 or 180 hp (130 kW) 400 cu in (6.6 L); those two engines standard on the LJ and SJ models, respectively.  The original thinking on the 301 CID engine was that the weight savings from using a significantly lighter engine would cancel out the horsepower loss from the smaller displacement.  This turned out to be a major miscalculation and 301 equipped cars became much less desirable among Grand Prix enthusiasts and collectors in later years.  The 301 also had a knocking (pre-ignition) problem that was later determined to be caused by the shape of the combustion chamber.
Each of those engines were Pontiac-built units as in previous years, but offered in 49 of the 50 states. Because Pontiac's own V8 engines could not meet the more stringent California emission standards set for 1977, all Grand Prixs (and other Pontiac models) sold in California were powered by Oldsmobile-built engines including Lansing's 350 cu in (5.7 L) "Rocket V8" for J and LJ, and the 403 cu in (6.6 L) Rocket V8 standard on the SJ and optional on the other two GPs in California. Due to a shortage of Olds 350 engines resulting from record sales of Cutlasses and reduced production of that engine due to a plant conversion to build a Diesel V8 beginning in 1978, a few 1977 Grand Prixs destined for California reportedly came off the line with a Chevrolet-built 350 cu in (5.7 L) V8.
Grand Prix sales increased to an all-time high of over 270,000 units for 1977, the last year for this bodystyle, despite competition from a newly downsized and lower-priced Ford Thunderbird introduced this year and a restyled Mercury Cougar XR-7 whose bodyshell switched to the T-Bird this year from the discontinued Ford Torino/Mercury Montego.
Pontiac Grand Prix