Dumb question (about intake manifold gasket) for the day

Thanks for the input, I think I'm going to opt for no end gaskets. As far as the heater goes...It's just weird that it got FIRE hot before I changed the intake, now it doesn't work. It was a pretty big vac leak, about 6 inches alongside the intake. Also, the temperature started reading at around 230, even while cruising, with a 190 thermostat. Not sure if the vac leak was causing that. My mileage was also HORRIBLE, I'd lose a quarter tank just driving around town for 10 minutes, casually cruising. I sure have learned a lot, mostly lessons of what NOT to do in the future! Again, thanks for all the advice, it's always much appreciated