Mamiya TLR left hand 'flash grip'

[Neil Grant]

...is it possible to attach a quick-plate to the underside of the plate? This is not possible with the grip I already have - it's the one with the built in trigger.

 

[MattKing]

The multi-angle version has a tripod connection thread, so yes for that one.
For the older, simpler one, I have an old one that was modified to add a tripod connection thread to the to the camera attaching bolt, so I can do it with that.
If I were to do the modification today, I would have that bolt taken out and try to replace it and the attachment bolt in the quick plate with one, longer bolt - leaving the quick plate essentially permanently attached to the grip.

 

[Sirius Glass]

There are numerous left handed grips that will work with the Mamiya TLR. Just start searching and choose the one you want.

 

[MattKing]

The Mamiya left hand trigger grips do, of course, include a very good mechanical trigger that mates directly with one of the two shutter releases on the various versions of the RB67s and C330 bodiess, as well as the special anti-twist locatng pins that mate with the matched holes on those cameras.