For (V-18) AQ280, 280T, 280PT, 290, 290A drives
Outside Diameter: 4-3/4″
Mounting Holes: 3-1/8″ center-to-center
EMP Aluminum anodes conform to Mil-Spec A-24779(SH)

also crosses with:
Canada Metals CM875815A, CMV18A
Performance Metals 00161A
GLM 12787
Technoseal 00703AL