This has good pictures of the spring drawbar mounts on a Firefly. The addition of the tail smoke meant the bar itself had to be removed but that would have post dated the fitting of the springs and by then, the need for tanks to tow guns had presumably diminished.
Tanks fitted with the offset hinged drawbar could retain them as that was fitted to the left of centre.
http://www.primeportal.net/tanks/rob...rman_vc_17pdr/