5th gear...!

Hi everyone,

I need some advice about my 87 cab. I have just replaced my gear box as the 5th gear decided to blow it self to bits!!! before it did this i noticed it was jumping out of the said 5th gear at speeds of 70 mph or over.

The gear box i have fitted was a second hand number with 85000 on it and it seems that i have the same problem of it jumping out of 5th gear and sometimes 3rd.

Can anybody tell me what the problem might be E.G gear linkage or something else.

Any advice would be very welcome
Rich
p.s the clutch is slipping too

check there is oil in it, they can overheat and jump out of 5th

Have just checked the oil and it seems fine. Should i add one of those gear box additves???

Could the gear linkage need adjusting? Is it hard to get it into the gears?