I havea 2003 f-150 with what looks to be a hurst 5 speed manual transmission. When I'm driving there is grinding ccshhh kinda sound. It's really quite in all gears but gets louder as speed increases and especially in 5th gear it's loud. It had anew space cylinder and clutch kit out in it with a new throw out bearing put in. Its full of fluid too. The grinding only occurs when I apply gas as soon as I let off the pedal it goes away/ or extremely quote to where it's nearly away. Also if I push in the clutch alittle the sound stops little by little until the clutch is all the way in. Also I tried to like push my shift left and right and up and down thinking maybe the hear sweetening all the way but nothing helped. Now if I were to change the fluid. What's a good fluid you recommend ? Thanks for all the help and sorry about the long post.

 

It may have a Hurst shifter, but it's a M5OD transmission. Sounds like it's rebuild time, I doubt a fluid change will help. It takes ATF.

 

Does have the hurst shifter, is a very close shift pattern. It shifts good just got that ccshhh sound. Very rarely it'll go into a gear a little rough, most of the time it's me

 

The M5OD is known for having a weak input shaft.

 

So most likely a rebuild ?

 

Yep.