The Dexter Trailer Hub and Drum Assembly for 2,000-lb Axles - 7" - 5 on 4-1/2 # 8-257-5UC3 will use a # 10-9 seal that is 1.5 inches inner diameter and 1.987 inches outer diameter.
Crossreference numbers are:
Dexter 010-009-00 K71-301-00
Transcom 15191VB
National 474276\
NOK AR2266FO
Chicago Rawhide 14840 view full answer...