Has any one heard of a 2 3/8 x 8 backing plate? I've seen 2 3/8 x 6 but not an 8 thread. If there is such a plate would anyone know where to locate one? I was wondering about all of the different chuck mounts. Does anyone know of a listing stating the dimensions for all of the different mounts such as D-4, D-6, LO, LOO and so forth? On the LO mounts, are they tapered or does it have the same dimensions straight thru. Dick