Revell: M4A3 Sherman & T34 Calliope Rocket Launcher (03074)

From Wikipedia:

The Rocket Launcher T34 (Calliope) was a tank-mounted multiple rocket launcher used by the United States Army during World War II. The launcher was placed atop the Medium Tank M4, and fired a barrage of 4.5 in (114 mm) rockets from 60 launch tubes. It was developed in 1943; small numbers were produced and were used by various US armor units in 1944-45. It adopts its name from the musical instrument "Calliope", also known as the steam organ, which had similar lined pipes.