Time Capsule HDD Upgrade A1355

Hi new to the forum so hello😀

As the title says im looking at upgrading the HDD in my time capsule as ive run out of space on the 1TB!

I belive its a 3rd generation (late 2009) model A1355, i was thinking about a 3TB upgrade but ive heard it could be maxing out the power supply so im quite happy to just go with a 2TB as the original 1TB has taken me 4 years to fill so hopefully it would last another 4 years!

My question is which HDD? Im from the uk and ive searched for compatable HDD's but with no luck as most of the HDD suggested in certain threads are now no longer availble!

Any help or advice is much appreciated

Thanks

Lewis