57 plate astravan, noisy 3rd/4th gear

[Buffalo]

Supercharger like whine (I wish) in 3rd and 4th and occasional graunching when going from 3rd to 4th - usually if try a fast change; keep it slow and it's mostly ok. It's on around 113k miles - is this a common thing or has the gearbox been abused in its past? Wasn't me gov, only had it just under a year...

Thanks!

[Buffalo]

Most of the M32 issues suggest 5/6th go first. Mine sound fine. I assume it is a similar issue though?

I did poke around on the Internet a bit more and learn that 3rd and 5th are on the same shaft but 4th/6th are not.

[Buffalo]

Well, it is getting harder to change gear when cold now. OK when warmed up but still occasionally grinds from 3rd to 4th.

Do you have the name of good specialists for rebuilds and rough idea of costs?