I've had two of these over time, and have been unsuccessful both times exhaustively looking for the special cable release. It's very unique on the end that goes into the film back, being tapered with a collar that engages inside the back. The little lever next to the hole on the bottom moves a lever inside that engages the cable.
The current back I have needs a rebuild, with frame spacing being whacko all over the place. I sold my near mint Mamiya Universal system a few months ago.
I also have spoken a few times with the man who many consider the guru of Mamiya Press and Polaroid 600SE. His name is Tony Sansone, and while hard to find, he can be located by visiting the family Virgin Oil web site for Kreta Reserve Virgin olive oil. He has many new and refurb Mamiya Polaroid parts and does rebuild all these cameras/lenses/shutters.
http://members.cox.net/gmhsint/
I know he is active because he recently sold a new film back to the fellow who bought my Mamiya Universal. Prior to that, I purchased the format masks for the multiformat back that shoots 6X9, 6X6 and 6X4.5.
The type III back that is shown in the previous listing is attached to and should be removable from the Polaroid 600SE adaptor with the split claw feet. This back should fit all Mamiya Super 23, Mamiya Universal with no-split claw back adaptor and the adaptor that comes with it.
I would presume to be able to buy that combo and then sell the adaptor itself to a Polaroid owner for good money, recapturing a good portion of the successful bid.
The S curve on the Mamiya K-type and Type III backs is reputed to be the reason for a much better than average film flatness experience. I believe that from my usage over the years.
While the Super 23 offers some perspective control, I believe it only does so on the collapsible 100mm 3.5 lens. I do not think the 65 collapses into the Super 23 body to allow GG viewing With perspective control.
The 100mm lenses came both in the collapsible and non collapsible focusing helicoils. Having had Super 23's I have never seen another lens capable of using the GG perespective feature outside the normal focal length 100mm.
The Super 23 is a tank and a good system camera base. The Mamiya Universal has numerous additional accessoried and capabilities.
I conclude and say here that the Super 23 is a great camera for taking pictures, and the Mamiya Universal is superior if you want to spend your time hunting and paying relatively high prices for obscure accessories. Oh, yeah, it's also a great shooter.
Last point, the lens/shutter/helicoils were different, by contract, from Mamiya to Polaroid to prevent loss of lens sales to either company. A lens helicoil for Polaroid, and the film back adaptors will not fit on a Mamiya body ever, without modification or purchase of proper components.