Side Rail Carriage Bolt 4308-01123-20 #8-32 x 1-1/4" Chrome
Side Rail Carriage Bolt 4308-01123-20 8/32x1-1/4" Chrome Order Code - HW142
Shown on the left of the second photo fitted with matching keps nut HW143
This is the smaller size used on Bally and Williams side rails.
For Data East you may need the larger size HW132 and KEPS nut HW133 shown on the right of the photo