Corey Dennis

Hi ZInDC, First off, congratulations on potentially picking up a Series I 240Z! They are incredibly special cars and it's smart to do your due diligence before buying out of state. To answer your question, your mechanic is looking in the right general area, but it can be notoriously difficult to spot. The engine number on the L24 engine is stamped directly into the metal of the block (not on a plate). Specifically, it is located on the top passenger (right) side of the engine block at the rear, right at the mating surface where the cylinder head meets the block, between the #5 and #6 cylinders [[1], [3], [6]]. The reason your mechanic can't find it is likely because it's tucked way in the back near the firewall. It is heavily obscured by the brake booster, the rear carburetor, and the distributor. On top of that, after 50 years, that little machined pad is probably caked in thick grease, oil, and dirt. Tell your mechanic to get a good flashlight and an inspection mirror, spray it down with brake cleaner, and hit it with a small wire brush. The stamping should start with "L24-" followed by the numbers. You can then cross-reference this with the number he already found on the passenger side strut tower to confirm it's a match. If it turns out the original block is cracked, hopelessly rusted, or the numbers were ground off and you need a replacement, you have a few options. You can hunt down another numbers-matching L24 block, or if you aren't a purist and want to do a wild custom build, there's actually a REDACTED on a local classified site right now that a lot of guys are swapping into Z cars for track builds. However, for a beautiful Series I, keeping the original L24 is definitely the smartest move to preserve the car's classic value. Once you get the engine sorted and confirmed, I'm curious about the rest of the setup. Does the car still have the original twin SU carburetors, or has the previous owner swapped to Webers or an EFI setup? Also, what color is the vinyl interior? Good luck with the purchase! Let us know what the mechanic finds.