Where does this washer or shim go?

[tonyk72]

After pulling the motor, transmission and bed on my Buffalo I started reassembly. I replaced the bearings on both rear axles. I got the motor back in and came across this washer in my bucket of parts. I don't think its the shim/washer for the axles because I kept close track of those. I know the grinder marks came from me when I tried removing or cutting something off...but I can't remember where it came from! It's 2" outer and 1" inner diameter.