I recently bought a rebuilt gearbox from Mini Gearbox Ltd and had a very good experience with them. My contact there was JTee who was very helpful and took the time to answer all my questions I had. The unit came with a free clutch, no core return and free one day shipping from the UK to The US. They have a listing on eBay as well as on there own web site. I have about 152000 miles on my 04 non S mini and I will try to update this post every so often to let you guys know the mileage I have on the rebuilt gearbox. So far ver pleased with the rebuilt gearbox.

 

It's rare that people proactively post about vendors that gave excellent service ( it's usually the bad ones that get the most attention ).

On that note, I had a great experience getting my supercharger rebuilt by autoxcooper last year. Dustin was very professional and accommodating to my special requests. He's a little more expensive than some other companies out there, but I'd rather spend a little more knowing I won't have to worry about anything.

 

Update, We now have 160,000 miles on the new transmission and at first the unit was a little stiff but has now settled in perfectly. And according to John T at Mini Gearbox this is why,
“you may find a different feel to the transmission as we now only fit Steelsyncro's into our transmissions.

Its probable that your old unit had fibre 3 piece syncro's which will wear out and then crunch.

The steel ones we use don't wear out as long as there's oil in the transmission, the trade off is they can be ever so slightly notchy when there first put in and i get a few comments that the unit feels different, almost industrial type of shift.”

Other observations are this transmission doesn’t seem to be as peppy as the original especially 1st gear. We have no leaks and overall we’ve been very pleased and would not hesitate to buy from Mini Gearbox Ltd again.