Is your transmission noiseless now in all gears?
I have a semi faulty gearbox which makes droning noise in all gears and "whistles" in 5th and 6th gear.
Plan to remove the gearbox in the next month or so and send it in for repair
I think it's cheaper than if they also must remove and reinstall it.
My gearbox had a faint whirring noise in all gears, whether the clutch was engaged or not or even if in neutral when driving along. In the last month before we rebuilt the box, this got significantly worse. It sounded like a lathe in the background - obviously the dashboard / carpet etc offer quite a bit of sound deadening but I knew what had to be done.
Upon removing all three gearshafts, all six main bearings were pitted. Luckily no lumps of swarf. The magnet had done it's job and collected what looked like a small amount of very fine filings. The oil was pretty clean but you could detect a trace of a very fine contaminant - probably from the rollers in the bearings that had deteriorated over time.
We stripped and cleaned each shaft, replaced all six bearings, cleaned out the inside of the gearbox casing. Once together, we put in a couple of litres of diesel and ran the car up on the wheel-free in second gear (with no acceleration) to flush out any last contaminants.
You can't re-shim the gearbox unless you want major hassle (only two sizes of shim are available anyway) so you can use the original shims. You obviously have to ensure that everything is back as it should be and the shims / bearing races are fully pressed 'home' to avoid any gearbox disasters once you run the car up.
We then drained and refilled with Fuchs Titan 75-80 fully synthetic gearbox oil. Currently running with 2.7-litres (recommended amount is 2.4 - 2.4 litres). I may top up with the remaining oil as some seem to think this may be worthwhile too. The transformation upon completion was instant and very noticeable. It's amazing how loud it must have been and how much I must have got used to the noise. The gearbox is now silent in all gears and the car is a pleasure to drive now.
I was fortunate enough to have some help on this so it's only cost me about £200 for the parts and oil but you should be able to get it done for approx £600. Warren at WG Motorworks was also very helpful for advice. He repairs these gearboxes week in, week out - WG Motorworks | Tuning, Conversions, Maintenance and Repairs
He is a Vauxhall specialist (some models also use the GM M32 box) but has also repaired some Alfa 159s.