I used to race the SC18 many years ago, there are still some SC18 bodies on ebay:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=sc18+body&_sacat=0
the only catch is you will need to convert the truck to buggy arms to get the wheels under the body ;)