the 3/8" you were referring to?  Being imperial, would it object to a metric (6mm) tap?
LBD  -the 3/8" is the socket drive (ie: 1/4", 38", 1/2") or 9.5mm drive and I don't know the diameter of your crank shaft on the DP but I checked mine with a digital caliper and it was a little over .500.  I filed it just enough to get a 6 point socket on but not so much that the factory handle didn't fit and work.  I then drilled and tapped the socket to accept a 1/4-20 screw to use as the set screw