I have a 1967 Mustang Coupe. It came with a 289 that has been bored, stroked, polished, ported, you name it. Upon inspection, the block numbers make it out to be a 64' HiPo block (not that it matters anymore). We picked up a 68' 4-speed toploader to mate up to it. I purchased the correct bellhousing to connect the 68' transmission to the 5-bolt motor. But, the slip yoke on the drive shaft i have is too small for the output shaft on the toploader. I looked in a parts book, and there only seems to be one size slip yoke. Any ideas on what's going on here?