Some might have heard this. (Found at hondaswap.com)
A woman called an auto parts store and asked for a 28-ounce water pump
"What?" asked the confused parts guy.
She said, "My husband says he needs a 28-ounce water pump."
"A 28-ounce water pump? What kind of car does it fit?" asked the parts guy.
"A Datsun," replied the woman.
As the parts guy wrote down her request, a light went on in his head.
"Oh, yes, ma'am. We've got 28-ounce water pumps," he said. "We also have 24-ounce and 26-ounce pumps." "Finally," she said. "You're the first place I've called that knew what I was talking about."
"Yes ma'am," said parts guy, smiling, as he jotted down "Datsun 280Z water pump..."
Post up other Z or Datsun related jokes you have come across.