The above photo seems to make the bay platform and siding appear shorter than they actually are so I've just taken a photo of a 2-car DMU standing at the buffers on the storage road for comparison. There's sufficient room for a 3-car alongside the platform so that's fine.
Here's some photos of a few other DMU's that are now part of the Worsley Dale roster.
Bachmann class 158 2-car DMU in National Express Scotrail livery. This livery is from the period March 1997 to October 2004.
Bachmann class 150 DMU, again in National Express Scotrail livery.
This is a Realtrack class 156 DMU in First Scotrail 'Barbie' livery. The 'First Group' franchise existed between October 2004 and March 2015. This model is sound fitted.
Finally a Bachmann class 170 Turbostar 3-car DMU in First Scotrail livery. Like the Bachmann class 158 pictured above, this model is unfortunately not DCC ready so needs a DCC chip hard wiring in order for it to work on Worsley Dale. Plenty of work for me to be getting on with.