Hi Mike
the gun is
QF25MkII
MO 1942 p   Jacket number L/6998
Cwt8 Lbs4
F16637
Breech  25Pr MkII M.O. 1942
Trail saddle 25Pr No11 Mk1
Trail Carr 25Pr Mk1 l L l
Ruwolt 1942
Reg No 5116
The cradle is the cast type and the trail is riveted. 
I Haven't seen a breech with the manufacturer M.O before which I take means Maribyrnong Ordinance factory. 
Gun first issued to Qld 21 Field regiment ...I hope 

 as that would tie in with the FAT and the Stuart...