There is a picture in the Warpaint of an AS Mk.5, and the ASV is a much fatter pod (than ASH) carried under the starboard wing. There are no pictures of this pod with any other navy. However, the text does mention TBM-3W and 3W2, and TBM-3S and TBM-S2, so the terminology appears to be that of the USN.
However, ASV 19A appears to have been a British design.
http://www.ekco-electronics.co.uk/ASV19/ASV19.htm
so whatever the 2 suffix may have meant to the USN, it is unlikely to be a reference to this ASV.