These companies have been very reliable dividend payers over the past couple of decades.A stable income stream is the cornerstone of a worry-free retirement. By receiving reliable payments, retirees can focus on enjoying life rather than stressing over expenses. The right investments are crucial in making this possible.Investing in high-quality dividend stocks can be a great source of reliable retirement income. Realty Income (O 1.12%) and Oneok (OKE 0.63%) have each demonstrated the durability of their div ...