Selling a Freelander and buying a D3 isn't what I'd be doing. The D3 is easily 10 X less reliable than an FL, and so is massively more expensive both financially and emotionally.
The D3 engine is a dog, with serious design flaws, like crankshaft failure, turbo failure, timing chain failure, impossible to remove glow plugs, suspension issues, rust issues and so on.
The Freelander engine is for the most part free of design issues, with just the occasional issue to sort. The FL drive train does have a few issues, but those are easy and relatively cheap to sort compared to a failed D3 crankshaft.
As for the D3 front end noise, then yes it's likely the diff. These Dana diffs aren't very good, and use cheap bearings, which delaminate under load. Unfortunately the diff design is compromised, as the same bearing is use to support the diff assembly and drive shaft, so it fails about as often as a Freelander 2 rear diff. Unfortunately the D3 diff is much more expensive, and much harder to remove than the FL2 rear unit. I rebuilt my D3 front diff, but it's a job for a seasoned professional, with experience in diff rebuilds. It's a full days work to remove and rebuild, with a second half day to put it back together again.
For me, a Freelander is a vehicle that is both good to drive, with relatively little worry about it breaking big time.
I was so put off by my D3's unreliability (it had full dealer history too), and generally worries that it might well return from every journey on a breakdown truck, that I bought a Freelander 2 as a replacement for my D3.
The D3 is hideously expensive to maintain, costing me easily £2k a year in parts, so after 3 years and £10k spent, I sold it and haven't regretted it one little bit.