For the final drive housings, I found some AFV Club parts, from a sprue from their M548 that’s also included in the YPR-765 kit, leaving these bits spare (among others):
However, there is a thick bit on the back that’s used to locate them in the M548 hull, but of course I didn’t make any holes in my M113 hull for these. Luckily, it was easy enough to saw those bits off:
Don’t go all the way through in one go, but saw to the middle from all sides, as that gives much less risk of ending up at an angle. All that remained was a little clean-up with a file, after which I could glue them to the lower hull sides:
The drive sprocket is
Tamiya, from the spares box, which, surprisingly, fits perfectly in the AFV Club final drive housing.
I glued the cut-off bit to the inside, but had to fill the big hole in it with a Hasegawa 1:72 scale Panzer IV roadwheel, which required opening up the hole a bit more.
I then put a piece of plastic card, of the same thickness as the lower hull sides, to fit between the two sides of the final drive housing, but larger than necessary. That allowed me to mark around the outside of it with a pencil, remove the card and cut it approximately to size. I then re-inserted the pastic and filed it to fit the housing (you can see this in the photo above). Repeat three times, so I had four pieces: two to put between the two halves, and two as the sides of the bulged bits of the nose plate.
Next, the nose plate itself. I had already cut this (see above) but it looked crooked, and turned out to be: 1.5 mm different in height between left and right. As the short side was too low, the part wasn’t salvageable, so I cut a new plate for it. I then glued on the two curved pieces I’d made:
When this had dried, I re-cut the “notches” for the final drive covers to match the curved plates, attached the nose plate to the hull floor and also waited for that to dry:
Then, I took some plastic strip of the right width (cut from 1 mm plate) and curved it, then stuck it in the opening:
This way, the strip is braced against the plates, preventing it from opening and pulling away from the plates. After drying, all that remained as to cut off the excess bits.