RAF North Creake Halifaxes – Assistance please

I have been contacted by a gentleman who is trying to learn more about his uncle, Flt Lt James Douglas Murray, service no.173769, who flew from RAF North Creake on Halifaxes in 1945. He knows that his aircraft was coded L, but is not sure if he was on 171 or 199 sqn, so I assume could have been EX-L or 6Y-L.

Can anybody identify the likely aircraft serial number and / or provide the names of his crew

Thanks Ian