R380 gearbox noise

hi all, im new to these forums but i have a 94 300 tdi Discovery in armada gold ..shes fantastic ! goes like new only 99k on her ..but i have a wee problem ..the gearbox tends to be quite noisy in 4th and 5th gear. i have a receipt for a gearbox rebuild at 63000 miles im just wondering what is it ?? i kno the early r380s had a weak input shaft ..perhaps this is the problem, however the rebuild was done by a discovery specialist ..as the car has a full service history i assumed they would replace the weak input shaft with the improved one. maybe im wrong ! The car still drives great the gears select as smooth as silk apart from whining noise ... im really stumped ..i hope i dont need a new gearbox. i have fotos of her if any body wants to c.
thanks chris

sorry no idea about the box but i would like to see your pic's

hi wats ur email address and ill send them ..wat do u drive
any fotos ?

mines a 97 300tdi ES with 80000 ish on the clock,i've had her for 3 years and it's been a good truck. you need to keep on top of the niggly faults or else they acumulate quickly into long list. i've become quite efficient at changing door lock springs and electric switchgear and for me this is part of the enjoyment of owning a disco.(i tell myself that anyway)
my e mail is: [email protected]

Check your oil level.