I had dealership fix and reseal the original sharkfin twice. Each time the problem returned within a year. I just had the dealership replace the shark fin with new design. GM takes little to no ownership for this problem. I have the 2015 duramax 3500 and water was pooling on passenger floor board, lost all navigation feature. I am satisfied this time it is fixed., but time will tell. The small gap that was in back of the original fin is now replaced with a solid gasket seal. Dealership charged me $550 for replacement and installation. Any silicone temp fix will not have long lasting impact, replace it and save yourself the future headaches. I feel your pain, love this truck but cant believe they dont do a recall and fix this problem without putting the financial responsibility to loyal customers.