I believe the shop was trying to say that "THEY" don't sell any bodies that are "DIRECT FIT" but generally you can make any 325mm body work with minor modifications. There are plenty of aftermarket mounts you can use if needed, I already see you upgraded with the STRC mounts anyway so I don't...
that is a standard 2WD SCT and any SCT body based on a 325mm wheelbase will fit perfectly fine:
https://www.associatedelectrics.com/teamassociated/cars_and_trucks/SC10/Race-Spec/specs/