LE-TRA versus Transportation Management

Hi,

we (my company) volition motorboat SAP S/4 HANA EWM astatine 1 of our lawsuit successful the adjacent future.

In the past they usage LE-TRA which should beryllium replaced by a SAP Transportation Management (TM) solution for basal shipping astatine outbound.

My questions:

- What is the successor of the LE-TRA customizing entity "Transport relevance" successful TM?

        - If nary successor is existing, what is the trigger for TM to make Freight units for peculiar deliveries?

- Are freight units needed successful immoderate case, respectively what are freight units utilized for?

- Can I make a thoroughfare freight bid with allocating Transportation units alternatively of freight units? 

Many acknowledgment successful beforehand for the answers!