The Type A engine was Toyota's first production engine, being produced from 1935 through 1947.
The Type A engine was a straight-6 engine
This engine was a 3,389 cc (3.4 L; 206.8 cu in) pushrod, overhead valve, 6-cylinder, three bearing engine copied from the 1929-36 Chevrolet Gen-1 3 bearing Stovebolt L6 OHV engine. By virtue of a modified intake manifold it produced 62 PS (46 kW), while the Chevrolet engine produced 60 PS (44 kW). GM used a number of local Japanese suppliers for the smaller engine parts (e.g. carburettors). Toyota was able to use the same suppliers for its cars. The parts were identical enough that pistons, rods, valves, etc. could be used in both the Chevrolet and Toyota engines interchangeably. There are several recorded instances of parts intended for one being used to repair the other
Toyota had initially considered copying the Ford flathead V8 because it was the most popular engine in Japan at the time. However, the machining of 2 separate banks of cylinders would add too much to the production cost, so the Chevrolet engine was copied instead.
Other references to the Chevy engine claim different power figures. Different manufactures used different measuring techniques (e.g. with or without the generator/alternator connected), engines differed from year to year and that some manufacturers simply lied. In this case, Toyota did back to back comparisons using the same techniques, so it is likely that the Toyota engine did in fact produce slightly more power than the Chevy engine on which it was based. Also, the Chevy engine was likely to be a year or two old, so the current Chevy engine may have produced even more power.