This lower gear set is in a DPX-A or DPX-R which were drives that only lasted a couple
of years. These drives were discontinued years ago (1998 or so) and as there were
not many of them around parts are very difficult to find.
I don’t think you will be able to find your gear set. You might be able to find a complete
used lower unit (part number 3858743 1.47:1) but again it will be difficult.
You might want to consider changing over to a new drive. If you give me your engine
and your actual drive type, I can quote you some options. But you are talking in the
$14K range I would think for a new transom shield and new drive (or maybe good used).