No matter if the body has broken, or you just want a spare lying around in case it does break, you might find this useful.
From Amazon
Tamiya 51613 Car Body Set Buggyra Fat Fox Part Model Making Accessories, Unvarnished
eModels
Tamiya Spare Parts Buggyra Fat Fox Body # 51613
Model Bau
Tamiya Buggyra Fat Fox Body 51613
Conrad Electronic
Tamiya 51613 1:10 Car body Buggyra Fat Fox Unpainted, uncut