Can you replace a 3 speed manual transmission with a C4 ford transmission in a 1961 Ford Falcon?
Ya sure can sure can, you may have a driveshaft and spline
issue, I took my old one to a driveline shop and had a new one
built to fit. The 3 speed trans is a lot of times paired with a 7"
rearend where the c4 is usually paired with a 9" so get both
driveshafts and have a hybrid made.