Euroroc II wrote: > Me thinks the mkI is a type 53 and the mkII is the type 53b... the 'a' > is implied but was not applied when the mkI was first developed... > > -Raffi > > I concur. There is no Type 53a per say, just a 53 = up to 1981 inclusive & 53b = 1982 and beyond. hth, TBerk