Starter replacement part number needed?

Item 5 in the image is the "Starter Plate" it is what Suzuki calls it. With Suzuki out of the US market finding parts isn't fun. I believe the plate is supposed to act as a shim as well as a block off for the extra space around the starter. The shim is so that the starter Bendix doesn't bottom out on the ring gear and cause damage. As finding one on the shelf is likely not going to happen, I would probably make one. Use a bore scope camera to look in at the ring gear and starter, Watch where the starter pinion contacts on the ring gear. Ideally you want it centered on the ring gear. The plate could be mage of some light sheet steel. Cut and file a hole in the center that the starter can fit into. Then use a marker to draw the starter outline on the plate with enough extra on the side toward the block to cover the hole in the mounting. Trim it up and then mark and drill the holes for the bolts. Now you have the plate. Or if you have one that is rusted, use it as a template. You could also use thin cardboard to create a template and get it to fit correctly, then use that to make the steel plate.

Well, it's a J20A Suzuki engine, it was used in 99-03 Suzuki Aerio and the Vitara (aka Chevy Tracker) However even those are scarce in salvage yards. I found about 5 of each when I just looked. If the starter on it works or the one you replaced wasn't grinding, I would say use some thin steel or aluminum to make one and call it done.

You're welcome. You have one of the orphans from that era, compounded by the issue of them not being a big seller even when they were still in the U.S. So there are not a lot of them still in salvage yards either. You might want to look online for one of the Suzuki groups, they might know of someone who squirreled away parts, or possibly have a connection in Japan where they still have the brand. (I wish they were still here; I had a Samurai back then and they still make the Jimny that those were based on, but they are not US legal when new and importing one that is 25+ years old with all JDM parts would give me a major migraine!)
Use the starter body as the template. It needs a hole large enough to match the starter body at the flange, the two holes for the starter to mount and then the rest just tucks in near the block to keep dirt and animals out.

I've made a ton of templates out of cereal boxes and craft paper over the years. Then transferred that to metal. Good luck and let us know how it turns out.

Great to hear. JDM parts are not something that they show in most domestic brands parts listings.