You can wire T/R ahead or behind the line card as long as the A/A1 leads are present and that the switch hook contacts make before and break after the ones controlling tip and ring (yellow/brown switch hook leads were used for the A lead closure in the set).
Because the tip and ring of the line passes through a sensitive reed relay on the line card, high ringing current draw on the station side can damage these windings. This would normally be due to a large number of bridged ringers. Also, later fully-protected line cards did not allow ringing voltage to pass through to the station side.
In general, an RJ12 was used ahead of the card for devices that required ringing, like phones, answering machines, etc. An RJ13 was used behind the card for devices that did not require ringing, like dialers, credit card terminals or modems. Regardless, the A/A1 leads were always the same. There are no separate line and station-side A leads.
