Which diagrams are booked for 2 coaches? I work at a station on the route and there are still a fair few 2-car 175s coming through, though I've noticed the 15:30 off Manchester has mainly been a 3-car set since December (used to be 2-car). Most of the Llandudno services are still worked by 3-car 175s too.
There's 4 sorry, although even 2 of these have seen 3 cars lately:
Diagram 1:
1W48 0503 Carmarthen to Manchester
1V39 1030 Manchester to Milford Haven
1B64 1708 Milford Haven to Cardiff
Diagram 2:
1W10 0615 Carmarthen to Manchester
1V40 1130 Manchester to Carmarthen
1W74 1658 Carmarthen to Manchester
(Although even this has been a 3 car of late)
Diagram 3:
1W05 0627 Crewe to Manchester
1V35 0730 Manchester to Carmarthen
1W64 1302 Carmarthen to Manchester
1V62 1830 Manchester to Carmarthen
(Again though this has been a 3-car of late)
Diagram 4:
1V33 0630 Manchester to Milford Haven
1W66 1308 Milford Haven to Manchester
1V64 1930 Manchester to Carmarthen
* Note that these diagrams are BOOKED for 2 car 175s; what actually turns up on the day is a different matter (you could get a 150 or a 153!)