I know a certain someone who used to use those strut tops as engine mounts in a 300zx (Z32). They seem to be a universal tool!.
Should sell them on Ebay for big money!

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As a side note, I've bee told the 260z's changed their strut tower design to accommodate for the Rally cars. Apparently the early 240z rally cars butchered their strut towers in the gruelling rallies of the 70's

. So they redesigned and strengthened them in the later RS30 series chassis.
*Might be the reason for the extra rubber.
Not that Lurch has any kiddies in the back seat

.