Stop holes are 4” on center. 1” drilled for 5/16” and 1-1/4” drilled for 3/8” plunger pin sizes. Fastener holes are on 4” center. Lengths are manufactured 1” longer than even foot measurement to provide fastener holes at each end of the track. ABI raised T-track has a full 5/16” clearance under lip to accommodate all cars and slides with or without nylon inserts.