So I bought a 66 Mustang and I have plans to modernize it a bit,It's a stock 6cyl 200 with a 3-speed. I'm trying to upgrade most of it's components over time as I have access to a workshop for free. One of the main things that I'm trying to switch out is the transmission, that 3-speed is not ideal for where I live(Fort Polk, Louisiana...there's a ton of hills on post). Looking for recommendation on where and what to buy for a transmission, I see a lot of T5 transmission for the 66 but this is my first time working on a classic mustang. I'm not trying to restore it, I'm trying to enhance it as this will be my daily driver on base so AC, suspension, power steering, fuel mileage is what I'm looking at. I have no A/C so...that's big on my list as Louisiana is nothing like California and tends to be moist... oh and I've anyone have tips or a direction on how to muffle or dampen the amount of noise coming from the engine. There's a ton of heat and sound pushing through the firewall and it can be distracting when you're driving.