3 ways:

1st
try to find out what the model name for the apc is with a model viewer such as this:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2853397387&searchtext=model+viewer
now it should let you know the model name, shown in the top left.
open up the console ~ / ` key.
type whereis (model name of apc)
it should show you which addons have the apc model. disable conflicting addons.


2nd:
get gmpublisher:
https://github.com/WilliamVenner/gmpublisher

find your workshop folder for gmod in steamapps/workshop
you will see a bunch of numbers, look for 4000, gmod's workshop id
look for this addon's id which is: 2197536127
use gmpublisher to extract 2197536127

then from there, look into the folder, and modify the model name to what the model name was ingame. It should replace it then.


3rd
Or you know, you could disable all mods, then go through them all for conflicts.