Many of the same parts were also interchangeable with the 1930s Chevrolet First generation Stovebolt engines, from which it was derived.

However, the machining of two separate banks of cylinders would add too much to the production cost, so the Chevrolet engine was copied instead.

[5] The design was based on the Chevrolet 207 engine, and built under license but with metric dimensions and minor revisions to suit the local market.

It had a four-bearing crank and shaft-mounted rocker arms, as did the Chevrolet engine.

Another bump, to 82 PS (60 kW) occurred at the time of the BM truck's introduction in March 1947.

[6] This was also the output of the improved engine fitted to the 4-ton BA and 2.5-ton BC trucks which were built until February and July 1956 respectively.

The 4,052 cc (4.1 L; 247.3 cu in) Type D was a larger version of the B engine developed in early 1944, featuring an increased bore while retaining the same stroke.

It was a direct response to a national order issued in 1940, instructing Toyota to develop a higher output engine based on the B.

[5] It did not enter series production, with Toyota instead developing the somewhat smaller Type F engine after the war.