I've read an article that says that u need to hold the shares...

I've read an article that says that u need to hold the shares for 45 days after the shares go ex-div. Is that correct>

No.

For ordinary shares (i.e., not preference shares), you have to hold the shares for 45 full days during the 'primary qualification period'.

The primary qualification period is from the day after you purchase the shares to 45 days after ex-dividend.

So if you bought the shares 60 days before ex-dividend, you can sell them on ex-dividend & keep the franking credit