Guys I need some help figuring out what this could be. I have knocking noise that I can hear and feel coming from the rear. But it only happens at cold startup and btw 0-10mph. As the speed increase it also increases. But after it gets warmed up I cant make it do it again, after I drive down the street thats all it takes to stop the noise. I have the 4r100 tranny with 3.55 slip. I have checked the fluid level looks alright. I cant figure it out, Any suggestions?