I have three Preston Integral Motor Mounting Brackets for sale. They mount on 19mm iris rods or you can use step down bushings to adapt to 15mm or Panavision-sized rods. I have had them for the last year and they have seen very little use. All are in excellent condition. I am only selling them because I have recently changed to Hill brackets.
DM1X Integral Mounting Bracket 19mm (Part #4308)- $330
(2) - DM2 Integral Mounting Brackets 19mm (Part #4309) - $330/ea.
Or buy all three for $900. Located in Los Angeles, will ship to US buyer for free or international at buyer's expense. Any questions, please don't hesitate to contact me.