Abstract: Employee #1 using his own job-made yard truck derrick with 2-part chain sling secured to hook on cable winch had hoisted front of vehicle up 6 ft to work beneath front end to cut motor mounts with gas cutting torch. Hooks on chain sling had been passed beneath bumper and secured to front shock bumper absorber bars with load equally distributed. Employee #1 completed task with cutting torch and was standing about 1 ft in front of the elevated vehicle when the rear of car settled slightly causing body to shift, which in turn allowed the hooks to detach, first the right & then left and the car body fell. Falling vehicle brushed Employee #1 chest and pulling his legs beneath the car. Employee #1 sustained fractures of the right upper leg and left lower leg. It was a cold morning, with the ground surface frozen hard early and it thawed as it warmed up. The thawed surface was wet sandy clay, which apparently let the rear of the car body sink.