I can confirm via the grandson of a 488th Sqn navigator Andrew John Broodbank that HK365 was indeed a Mark XIII. Broodbank has flown both in HK365 and with Vlotman. The fuselage code of HK365 is still not certain though...
Please have a look at his blog, following Broodbank's logbook, 70 years on:
http://broodyswar.wordpress.com/