The northern random unit generator produces anything in classes 142/144/150 &158. I assume 155 & 153 also turn up form time to time
Calder Valley may be a route which has each type of DMU Northern have booked to work on it. Although I've heard 144s are not as common as they were a couple of years ago and I've seen 158s on the Huddersfield-Halifax-Leeds service recently when that service used to be almost exclusively 142s and 144s.
I believe that once the new fleet arrives 2019 onwards rolling stock will be moved around the network.
Halifax is one of the routes named as a northern connect service. So new nrolling stock will be on this route from Liverpool via Rochdale , Hebdon Bridge.
In my opinion the 158s will be moved to longer commuter routes that go across the Pennines rather than short services.
It's worth noting that not all Northern Connect services will be 195s. 158s will continue to make up the numbers, while the Huddersfield via Brighouse will be 150s/155s. The non-Connect Calder Valley services will most likely be Turbostars.
Which will be the Southport-Victoria-Halifax-Dewsbury-Leeds services.
Of course...Which will be the Southport-Victoria-Halifax-Dewsbury-Leeds services.
No, that service will run the same route as the current via Dewsbury service and won't serve Halifax. It was my error that led to this off-topic diversion. Apologies!A reversal at HFX?