[Spridgets] gauge compatibility questions

[Chris Manuel]

Hi all-

I'm going through a box of car parts that someone gave me, and I came across
a tachometer (positive ground) made by Smith which says Cortina on the
front.  I also have a speedometer that sort of matches it but is the same
size.  The FoMoCo numbers also trace back to a '68 Cortina.  Both are 4".

Would these be usable spares, or is this just overflow parts from something
else they had? 

Chris

66MKIII
Milwaukee, WI