Ok you need to first either get someone to give you that trailer again or you have to give it to a friend who will then need to give it back to you.... once you have someone to give it back to you the next step is to do gctf to receive it.
The only difference is on the last step before you take the new one you need to call yours out onto the map. You will have to return your moc to be able to call it out.
Once yours is on the map then take the new modded one. Once you have the new modded one in your moc you then once again want to call for your aa trailer. This time it should be the bike/car you got glitched out in. If it is then drive it into you moc and accept the full alert . Done new modded aa trailer is now where it belongs.