They can’t legally post it
There’s no connection between The Statute of Limitations (SOL), which is the time frame to bring a lawsuit and the credit reporting period which is the time frame a debt can be posted on your credit report.
The SOL is governed by state laws, and for most debts it is less than 11 years. See this Complete list of SOL by State for your state.
The credit reporting period is governed by the Fair Credit Reporting Act (FCRA) which is a federal law. Most debts can be posted to your credit report for 7.5 years from the date of first delinquency, and this clock cannot be restarted. See this
complete credit reporting period list for more accurate information.
An 8 year old defaulted debt cannot be legally posted to your credit report. They CAN try to post it anyway. If they do – simply dispute it as being beyond the reporting period.
If the debt is beyond the SOL, send the collection agency a certified, return receipt letter telling them to cease all contact as the debt is beyond the SOL and the reporting period.
They will probably stop calling you, but will likely sell the debt to another zombie collector, and you will need to repeat the process.
For more important information about how to behave with debt collectors please see how-to-pay-off-debt.html.