Cummins first gasoline engine but
not their first non-diesel engine. Cummins has built spark-ignition CNG engines for over a decade, starting with a CNG 12L version of the ISX.
Cummins has produced the B6.7N, a spark-ignition CNG engine, also based on the 6.7 B-series diesel (like the Octane), since 2018. Stellantis (and FCA previously) use this engine in their Detroit-area and Windsor day-cab fleet for transporting parts and assemblies between plants.
https://www.cummins.com/engines/b67n-2018
Additionally, Cummins recently rolled out the big X15N, a CNG version of the 15L X-series diesel. It makes 500 hp and 1,850 lb ft torque.