A Series ___ Graflex SLR shutter curtain does not have the metal strips found on the Pacemaker Speed Graphic.
A Super D has a set of flash sync contacts inside the wind plate. The Super D is a Series D with factory built in flash sync.
The flash sync on a Super D is available at all speeds using long burn FP flash bulbs only and Open Flash drop curtain with faster duration flash.
The "Flash Sync" is a set of contacts that are closed by the curtain gearing as the curtain is released.
3rd party flash sync contacts were made for large format SLR's that attached to the body at the wind plate and were actuated by the wind key.
A flash bulb or electronic flash for Open Flash can only be connected once the curtain is set for the exposure as winding it will actuate the flash sync contacts.
No modification can be made to a Graflex SLR to get it to sync with an electronic flash other than open flash at O. A curtain opening takes 30 milliseconds to 45 milliseconds to travel from the top of the film plane to the bottom of the film plane in landscape orientation. A full power discharge on some electronic flash is 10 milliseconds in duration or faster.
See
http://www.cameraeccentric.com/html/info/graflex_16.html and
http://www.cameraeccentric.com/html/info/graflex_8.html
The flash sync devices for large format SLR's ocassionally show up on ebay.