past perfect

[Taka]

The car I sold yesterday had belonged to my uncle before.

If the part in bold was the simple past instead as:

The car I sold yesterday belonged to my uncle before.

would it still sound OK or not?

[Tdol]

It's OK, but I would drop before- the past perfect suggests the possibility that he had not been the last owner before the sale, but the past simple doesn't IMO.

[Raymott]

The car I sold yesterday had belonged to my uncle before.

If the part in bold was the simple past instead as:

The car I sold yesterday belonged to my uncle before.

would it still sound OK or not?

It's syntactically correct. But we'd almost invariably say, "The car I sold yesterday used to belong to my uncle."

[Taka]

It's OK, but I would drop before- the past perfect suggests the possibility that he had not been the last owner before the sale, but the past simple doesn't IMO.

Which 'before' are you talking about, tdol? The first one with the past perfect? Or the one in the simple past? Or both?

And with or without before, are you saying that the example of the past perfect suggests that the uncle might not have been the last owner before the author sold it?