Differential COVER Flange hub. 2-1/2" ID X 6-1/2" OD and these are my measurements.
8 Holes in both surfaces, total 16.
171854, 72027912, 1602370, 1652170, 2171854 Replaced by 2171854SM: COVER-DIFF...
BEARER Hub, Cast Metal with 4 outer holes .40"ID on 2.87" center diagonal,
3.62"OD x 1.25"ID on Large surface side and that only extends in .125", rest of hub opening is 1.54".
1.85" deep / thick...