QB Issue Resolution:
QuickBooks Mac Pro 6 is from 2004 I think. I don’t recall if that version has a convert to Windows function – it may and you can give that a try.
If you have access to a Mac running Mavericks or newer OS you can download the QuickBooks Mac 2015 trial for free, upgrade your QuickBooks Mac 6 file, and then File->Export to QuickBooks Windows.
Resolution for Issue 'How can I convert Mac Quickbooks pro 6 to Windows 7 Quickbooks 2014?' available: Yes (Solved).
Source: Intuit Community forum.
How can I convert Mac Quickbooks pro 6 to Windows 7 Quickbooks 2014?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.Support for Data Conversion
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