The Datsun 240z came with an inline 6 cylinder engine designated as the L24 (2.4 Liter displacement).
The Datsun 260z came with L26 (2.6 Liter displacement) and the Datsun 280z came with the L28 motors (2.8 Liter displacement). They all use the same timing cover.
The water pump is mounted to it and the Crankshaft seal is on the inside of it. The oil pump is bolted to the cover on the bottom left. The oil pump/ distributor shaft runs through it and the distributor bolts tot he upper right side.
The timing cover for the Datsun 240z 260z 280z has many bolts, many different sizes. I made this image to help identify them when I rebuilt my Datsun 240z Series 1 L24 motor. The 280ZX also has a L28 motor and the 280ZX Turbo motor is designated as L28ET and should have the same timing cover, also. If this is incorrect please send me an email.
Bolt specification info:
Example: M6 -1.0 -85
M6 means Metric Bolt with a diameter of 6mm
1.0 is the pitch of the threads, the distance between the threads in mm.
85 is the length of the bolt from end to end (Beware some bolt types are measured from the length of threads, excluding head length)
Bolts may also have a strength rating stamped on the head of the bolt.
Many people miss the top 2 bolts that bolt the timing cover to the head, they are often covered in grime and unseen.
When you are removing the timing cover be careful. Remove all bolts ( I would print this image and lay bolts where they go). When prying it off, work around it using a rubber mallet and plastic pry bar tool. Do not use metal hammer or prybar / screwdriver. Its made of aluminum and can easily be broken or scored. The crankshaft seal is a tight fit, the cover needs to be removed very slowly, mm at a time. Be patient!