a system comprising a type h tightlock coupler comprising a channel and an inner chamber , the channel running from a top side of the type h tightlock coupler to the inner chamber , and an anti - creep shelf disposed on an interior surface of the inner chamber , a plug comprising a first surface operable to contact the anti - creep shelf , the plug configured to fit at least partially within the channel , a link comprising a second surface operable to contact the anti - creep shelf and a hook , the link configured to fit at least partially within the channel , and a lock comprising a slot operable to receive the hook , the lock configured to fit at least partially within the inner chamber .