I’ll have to check after work to see if there’s a visual clue like a red border. I sometimes get confused between what was in the DLC and what was from Hospital survival which was added to the base game in an update. Full list of DLC equipment in the category rules
I've had a look and unfortunately DLC Suvival drops don't have a red border.
In case it helps here's what's allowed:
Chassis: Mk IV/Rank 9 and below
Maching Guns: Rank 10 and below excluding L-1 "Master Blaster"
Shotguns: Rank 10 and below excluding Crater Creator
Sniper Cannons: Rank 10 and below excluding M1600 Spurt Rifle
Grenade Launchers: Rank 10 and below excluding GL-V "Pitching Machine"
Artillery Cannons: Rank 10 and below excluding Smasher
Broadcasters: Rank 10 and below excluding Standard Laser
Light Turrets: Rank 10 and below excluding Ironclad Shotgun Turret, Massive Flak Turret
Support Turrets: Rank 8 and below
Heavy Turrets: Rank 10 and below
