Just be sure you break it in properly. That's where a lot of issues stem from, from what I hear.

https://www.f150online.com/forums/ot...procedure.html

 

I've heard that it could all have to do with the installation. I have FRPP 4.10 gears in my F-150, and no issue what-so-ever.

 

Thanks, the mechanic said he did the heat-cooldown cycle, and after about 200 miles we are draining and putting in the Royal Purple, the miles maybe a little different since it is a Mustang Mach 1 and not a truck. The installation is everything, my mechanic, put it together and tore down three times till he felt he had the lash and all specs perfect. He is in Blackshear and charged me $200, not bad for all he did, plus charged me the parts price and installed my fan free!! Thanks for all the responses!!!