underneath the body are 4-6 screws
that hold the chassis to the body.
you may have to turn trucks out of the way
to get at some of the screws. and all the screws
may or may not be the same size.
try removing the 4 screws at the 4 corners 1rst
before removing anything in the middle.
work carefully and when pulling the body from the chassis,
take care of any wiring whne removing and replacing the body
so nothing gets pinched in the process.
Work on a white towel for cushioning and if you drop
anything.
good luck.