[Healeys] curious

[healeymanjim at hansencc.net (healeymanjim)]

pulled the pistons from a BT7 and was cleaning them up and got curious as to 
the markings.  there is a diamond with a 2 in 
it stamped in the center of the piston and a marking that says front and above 
it is ID25.  anybody know what these 
markings mean.  has the diameter of a standard piston.