The closest I've found is the "Customers & Receivables->Average Days to Pay Report". Before customization, this report will give you the following fields:
| Type | Due Date | Num | Memo | Account | Class | Amount | Date | Paid Date | Avg Days to Pay |
You will need to filter/customize this report to get what you need. Use the Due Date to minimize the amount of data you pull. You won't get the number from the payment transaction but you will get the date. Partial payments won't be easy to identify. Not the best but it may work in some cases.
