ORIGINAL: siberianhusky
One thing that could be a problem, you have a really big gap between the stuffing tube and U-joint. That space combined with the U-joint could whip at rpm and chew up the stuffing tube and cable. I don't think you're running enough power to twist the cable but I'm pretty sure it will whip.
You usually keep that space less than a half inch.
The one other thing is it a cable with square ends that floats in the prop shaft? If it is you're ok for clearance at the drive dog, if it's a one piece cable and stub shaft you need to leave about a 3/16 gap between the drive dog and stinger to allow for a little shrinkage when the cable winds up a bit under load. Otherwise it may bind and chew up the end of the stinger.
I ended up using a solid coupler & ditched the U-Joint. The Cable is round at the end and I added a small gap between the prop and the end of the shaft. I did notice a bit of vibration but I assume that is the shaft vibrating in the tube and seemed normal. I do have another shaft that is solid with a flex end on it. Do you think that would be better?
Thanks for the help guys it's appreciated!