1968 D Cent On A Nickel Planchet ?

Hello roach,
One of the easiest ways to tell a lot about a coin is to weigh it. A scale that can weight down to the 10th of a gram would be helpful. That way when you find something that looks like wrong planchet or just funny you can weigh it and then compare the weight with the normal weight for that coin. If you want to see what a coin struck on a planchet of a wrong denomination looks like, Mike Byers and Fred Weinberg usually have some of these errors with pictures on their websites.

It wouldn't have been struck on a nickel planchet as the nickel planchet is larger then the cent it would not feed into the machine. Off metals are struck on planchets smaller then the coin the dies were intended for.
Does the edge look copper clad as a dime would from '68?

A standard copper cent weighs 3.11 grams ,, .04 of a gram is a very small difference, without having the coin in hand and from such a small amount of weight difference it is more than likely plated.

Metalman

I'll throw my hat in the "plated" ring.

Michael