Many folks have problems finding the serial number for a WD or WD45. I have posted several images showing the SN locations for B, IB, C, CA, WD, WD45, D14, D15, 190, 190XT, etc. that may help. I posted all that I could get my hands on. If you can provide others I'll be happy to post them too. Click on the link and select the AC Tractor Serial Number section.