Reverse Grumble

I went and looked at an 85 2001 tonight and when you put the boat in reverse it seemed to make a grinding or grumbling sound and it vibrated a little. I lifted the engine cover and it did not appear to be coming from the velvet drive. It sounded more like the prop was loose and or the shaft was moving in and out in reverse. But when we got the boat back up on the trailer it did not have any end play at all in the shaft or the prop. The only thing I found was that the rudder was a little wobbly but not much and the prop was a little nicked up but again not very much. The only thing I could think of was the sleeve that hold's the shaft on the underside just before the prop has some issue but again there was no movement and there was no visible sign's of damage.I have taken a velvet drive out and replaced the flex plate before but I have never had to do any overhauling on one before. Are they really complicted and if so does anyone know how much a used one should cost?

It only got worse the more throttle I gave it. My thing is I would almost swear it was not coming from the tranny because when I opened the engine cover it should have gotten louder and instead it sounded like it was quieter because the noise of the engine was drowning it out more. I really was surprised to see that there was no end play in the shaft or prop. Is there a bearing behind the drive shaft seal?

I am almost 100 percent sure the noise was not coming from the tranny. The problem is there is no where else that it could be coming from as far as I can tell.