We offer replacement spring assemblies compatible with various RV roller shades, including those similar to your part numbers 74.4209 and 1360115. To ensure the correct fit, please measure the diameter of the roller tube and the width of your shade. Based on the measurements you provided—inner tube diameters of approximately 0.89 inch and 0.95 inch—we recommend checking the Irvine Replacement Spring designed for Valu-Line roller shades. This part is available on our website and comes in multiple sizes to match your shade dimensions. If you need further assistance identifying the correct spring assembly or have additional specifications, please contact us with those details so we can guide you to the proper replacement part.