This mod adds rear 'hooks' to all ownable trailer chassis allowing for more variety in ownable multi combination trailers. Supported combinations include:

Box Trailers:
Rocky Mountain Double:
45ft Front + 28ft (adjustable)
45ft Rear + 28ft (adjustable)
45ft Spread + 28ft
48ft Front + 28ft (adjustable)
48ft Rear + 28ft (adjustable)
48ft Spread + 28ft
53ft Front + 28ft (adjustable)
53ft Rear + 28ft (adjustable)
53ft 3 Axle + 28ft
53ft 4 Axle + 28ft
53ft 4 Axle Steerable + 28ft

45ft Front + 32ft (adjustable)
45ft Rear + 32ft (adjustable)
45ft Spread + 32ft
48ft Front + 32ft (adjustable)
48ft Rear + 32ft (adjustable)
48ft Spread + 32ft
53ft Front + 32ft (adjustable)
53ft Rear + 32ft (adjustable)
53ft 3 Axle + 32ft
53ft 4 Axle + 32ft
53ft 4 Axle Steerable + 32ft

Turnpike Double:
45ft Front (adjustable)
45ft Rear (adjustable)
45ft Spread
48ft Front (adjustable)
48ft Rear (adjustable)
48ft Spread
53ft Front (adjustable)
53ft Rear (adjustable)
53ft 3 Axle
53ft 4 Axle
53ft 4 Axle Steerable

Chipvan Trailers:
Turnpike Double:
48ft Front (adjustable)
48ft Rear (adjustable)
48ft Spread
48ft 3 Axle

Additional accessories have also been unlocked for more trailers including:
Sideskirts for B-Double Box trailer chassis
Sideskirts for 32ft Box trailer chassis

Credits: Gdog900