This is the Trumpeter 00378 kit in 1/35 scale, of the ‘German Geschützwagen Tiger für 17cm’.
In 1942 Krupp started development on a heavy SP gun-carrier for the 17 cm Kanone or 21 cm Mörser by using Tiger automotive components like engine, transmission, steel road wheels and tracks.
Complete weight with an 8 men crew was about 60 tons, armor thickness was 30mm at the front and 16mm on the sides, a top speed of 45km/h on roads was possible.
The partly assembled prototype was found in 1945 by allied troops in Haustenbeck near Paderborn.
Source: Trumpeter website