Tach reduction gear

Ron Soave and I were looking at three tach reduction gears I have in my 
parts boxes.  We began wondering if the same gear that is found on the 
Frogeye Sprites was also used on any other English cars of the period.  
Donald Healey, after all, borrowed ready-made parts from a wide range of 
other cars.

Later, when I cleaned them up, I found that one had a number of 4302/00, 
while the other two had numbers of 4302/50.

Does anyone know 1) if the Sprite tach reduction gear was found on other 
cars, or 2) what is the difference between the two numbers (all are 
Smith's).

Buster Evans