Thanks for the info and help. Somehow I was convinced the fillets looked like silicone... glad I was set straight... you guys probably saved my bacon on this one. I was ready to use silicone. Finally got engine thrust set and the firewall drilled and ready to be glued to the fuse. Based on your collective info I plan on using a good epoxy and a micro-balloon/milled fiberglass filler. Thanks again. John.