Hey guys, I have a Steiner 420 that I am working on. I pulled it out of the weeds about a week ago. It had been sitting outside for 3-4 years. I have managed to get it running and turning but not moving. While taking a look at the rear axle, I saw a drain plug (of course) and another open machined hole. I cannot find any info about this. I have attached a pic hoping someone can tell me what the hole is for and how to close it up. It does not appear to be threaded.

