Axle & Transfer fluids

Hi, new Disco 2 owner here, 53 plate TD5

Today I drained all the old oil from the front and rear axle's and transfer box. Apart from being a bit gloopy, the oil was pretty clean and the magnets just had the usual gray fine gunge on them. The old oil, which I suspect is original smellled like EP80 or similar. I re-filled with 75W/90 semi synthetic

The only problem I has, was on the front axle magnet, there was a small roll/dowel pin stuck to it, about M5 dia by 10mm long.. It wasn't marked or chewed up, so it hasn't been crunched through any gear teeth.

Any ideas what it's come from ? I guess it could have been there since in was built or for the last 50K miles, who knows... If I hadn't changed the fluid I might never have known anything about it.
I'll just keep using it until something fails, then fit a 2nd hand axle or whatever..

Anyone else seen this ?
Thx
Mat

pin holding diff carrier pin in perhaps if so it will want replacing before diff breaks up, it could just be a pin from a previous diff ,its worth remove filler plug and checking using a torch youd need one wheel up to rotate the diff to check the shaft

Ah, OK yeah maybe from some previous work... I have a boroscope camera I'll shove it in the filler level plug tomorrow and see if anything's amiss ... it was half filled with black silicone sealant.