I think the age of the car and, also, whether you have owned it from new have a bearing on this situation.

If the car is, for example, several years old then it's not expected to be like a new car! Provided it runs well and can be driven OK then that's really all that matters. If you haven't owned the car from new then you don't need to say anything about the gearbox at all. There's no way of telling under who's ownership it was changed.

I think you're probably worrying too much but I admire your honesty, OP. This sort of thing is one of the reasons I won't sell cars myself anymore, I always trade them in and let someone else have the pleasure.

I can think back to some of the cars I've purchased in the past, particularly at the beginning of my driving career. Whether the gearbox had been changed or not would have been, really, of no consequence or interest as some of these cars had far more serious problems.

Would a used car dealer selling your car tell a prospective purchaser that a replacement gearbox had been fitted to it, assuming you had told him when trading it in? No, I don't think so, not unless it had been a brand new one!

I see your point but I'm sure about this situation.

The question is, 'Have there been any issues ?' Honest answer is that there have.

Worst case scenario there is a gearbox problem later with the car. Buyer told gearbox not original but a replacement.

Buyer aggrieved that he was not answered truthfully.

I don't know - its just a possible view.

Buyer can be aggrieved as they like!

Sold as seen and tested.

If he'd got someone to bodge it back together long enough to get to the end of his road, that's a different matter.

I rewire houses for a living. I don't get asked to put the old stuff back in very often.

The question is, 'Have there been any issues ?' Honest answer is that there have.

Worst case scenario there is a gearbox problem later with the car. Buyer told gearbox not original but a replacement.

The car has done 78K miles - things will have been replaced, mostly normal wear & tear, some maybe not. But it has been kept in proper running condition, so no need to go OTT pulling the rug from under your sale. By all means hand over all servicing records to the buyer - he can read them at leisure and discover that the car has been looked after.

If he asks explicit questions, answer truthfully. That's all there is to it.