Experience with the 155 mm howitzer on the M4 chassis suggested it might be possible to mount it on the Heavy Tank T26E3 (which was formally named "heavy tank M26 Pershing" in March 1945) chassis, and that the 8-inch gun could also be mounted as part of a planned "heavy combat team" using the same chassis (other members would be the T26E5 assault tank and T84 8-inch HMC).

[3] The chassis needed to be lengthened with addition of an extra road wheel, to give seven each side.

A limited procurement of four pilot vehicles was ordered in March 1945, and the first was finished in July of that year; only five would be built in total.

[4] The trials of the T92 and T93 showed that they would be useful in Operation Downfall, the planned invasion of the Japanese mainland.

The T92s and T93s were being readied for sending to the Pacific War but the Japanese surrender occurred on 14 August 1945.