Hello everyone, I'm new to the forum and am glad to be a part of the forum to contribute and learn from you guys. So, I have a 1974 C10 that had a TH350 and a 305 when i bought about 4 years ago. I've decided with the 454 engine I want to upgrade the transmission first. I've decided to purchase a TKO 600 5 speed from American Powertrain. My question finally is how much would I have to modify the transmission tunnel and floor so that the transmission would fit? it has a low hump floor so I'm thinking I will have to modify it. But I just wanted to run it by you guys to make sure. Thanks in advance.