Most likely scenario for an hour meter

Looked at the hour meter on the 70D grader I bought. It reads 4980 hours. Which of the following is the most likely?

* New engine was put in (can't find a serial on the engine to compare to the frame)
* Hour meter was changed
* Hour meter rolled over at 99,999
* The old girl really only ever put on 4980 hours

Option #2 by a mile! unless it just stopped counting instead.
Maybe #1 since you can't find the number.

Look along the lower edge of the block below the fuel filter tower and transfer pump. There is a flat machined there just above the oil pan, where the serial number of many D318's is stamped. This is in addition to the usual spot above the pony motor controls just below the head gasket line where you should see the two rivet holes where the tag once was. Should have been behind that tag too.