Join Date: Jun 2011
Location: Colorado Springs
I spent a lot of money and extra effort to install a TKO 600 in my 1970 Mach 1. So, what's the verdict? Oh man, is it sweet! No, it doesn't have the same feel as a classic Top Loader, but I like the way it shifts. I have only about 700 miles on the new engine and trans. The more I drive it, the better is shifts. On the highway, I'm absolutely thrilled when I can be screaming along at over 3,000 RPMs, push the stick into 5th and drop the RPMs by 1,000. (Pretty sure I smile every time I do this.)
In overdrive, it's more quiet for cruising. My Cleveland still effortlessly pulls the car up hills with no need to down shift. It uses less fuel. It creates less wear and tear on the engine.
So, yeah, I really dig my overdrive! I plan to drive my car a lot and on long cruises and day trips. So, for me, it was well worth it. If you're simply going to zip around town now and then, no, an overdrive likely isn't worth it.
In the end, it's up to you. I also went with Modern Driveline and I also used a rollerized version of the factory Z-bar linkage. I'm very happy with it.
Lately I'm seeing Top Loaders sell for pretty high prices. If you don't want your Top Loader, you could likely sell it for a good chunk of change to apply to your T5.