Couldn't find the belt for our 20+ year old vacuum anywhere else. Found it quickly on this site and vacuum is back as good as ever.
Center post-rght-for ada/asa/aua51/5112
4-120r,center post 7-9/16 x 27-21/32, 51 series
Buy this part and as many parts as you like and pay only $9.99 shipping, within the Contiguous United States.