Assume your leaks occur when the slides are open and not when they are closed. Unless you have upgraded your toppers, the metal portion of the toppers that came on the o3 allows water to pool on the top of the slides. The seals on the top of the slide are marginally effective in stopping the water from coming in once it has pooled. There is a caulking process that helps channel the pooling water to the outside of the coach that helps but its not 100%. Many 03 owners leave their coaches parked at a slight incline [usually to the front] so the water will pool less. PM me and we can discuss the caulking "solution."
2003 40' MDTS
Garden Ridge, Texas