In January 1977, the Fronte received some light alterations including new seats, a rectangular Suzuki badge in the front grille, taillights of a new construction, and a slightly remodelled engine lid with a somewhat wider recess for the license plate. This model is sometimes referred to as the SS10-2, to tell it apart from the pre-facelift model.
Suzuki's inability to fully meet the 1978 emissions regulations with the two-stroke engine compelled them to write a contract with Toyota to purchase engines from their subsidiary Daihatsu, Suzuki's main competitor. Beginning in May 1977 Daihatsu's catalysed 28 PS four-stroke AB10 engine was installed in the SS11, selling in parallel with the two-stroke at a slightly higher (by ¥18,000) price. Four-strokes had a "4" logo in the grille. These were very weak sellers, offering much less torque and drivability than their two-cycle brethren. Torque was 3.9 kgm at 3500 rpm, versus 4.6 kgm in the smaller two-stroke engine. At about the same time, in an attempt at meeting the tighter 1978 emissions standards with a two-stroke, the new SS12 Fronte 7-S was presented. It had a now even cleaner T4A engine called the TC53. "TC53" stood for Twin Catalyst, year 53 of the Showa era (1978 in the common era). This new, cleaner engine lost further power and torque though, now down to 25 PS, and still barely met the official emissions standards. A mere 6421 SS12s were built, compared to 66,540 SS10 Frontes.
The interim SS12 was replaced by the "full scale" 550 cc SS20 version presented on 27 October, with a slight facelift consisting of a new grille, redesigned cladding around the C-pillars, and a new dashboard. The SS20 is equipped with the T5A engine (first seen in the Jimny), with 539 cc it offered 28 PS at 5000 rpm and 5.3 kgm at 3000 rpm. To use up leftover four-stroke engines, the SS11 received the same facelift, becoming the SS11-2. The SS11-2 was fairly short-lived, though, as the T5A engine met emissions regulations on its own and Suzuki was now able to terminate their contract with Toyota.
The home market Jimny 550 received a facelift in 1977, introducing rear wheel arch metal flares and a bigger bonnet or hood with cooling slots above the radiator, while the export model LJ50s were instead replaced by the LJ80 (same external modifications but with the new four-stroke four-cylinder 800 cc engine fitted).

From June SJ 10 (SJ 50 or Jimny 55) new, taller engine hood with vents on leading edge. Stronger rear differential, widened rear fenders due to 100 mm wider track, front and rear. Gas tank increased from 26 to 40 L.
Four-stroke, four-cylinder OHC SJ 20 introduced in June for export only. From September available for home market.