I have a F150 with the 4.9 liter engine with a new 1 barrel carb. I have a vacuum leak at the base of it after installation. I went to order another gasket and now see that it mentions a spacer on the gasket description. Did these engines come with a spacer between the intake & carb? If so, where do I get a spacer? When I removed the old carb, I threw out the old gaskets / materials that were under the carb. The engine runs great with the new carb, but has a slight vacuum leak.