Quick Exploder HB measurement needed

[nvrstuk]

Anybody have a serp Exploder harmonic balancer laying around that can get me a quick measurement?

Looking for the measurement from the back of it that butts against the crank to the mounting face of the pulley.

Thanks

Here's a pic of something similar...

 

[EPB72]

Wher exactly you want measured 4 9/16 subtract 1/4 inch and that is the edge of outer groove of where belt rides

 

[nvrstuk]

Thanks, much appreciated.