RNS510 Upgrade.......which model number??

[sebastalona]

Hi,

I have a 2011 Passat Estate, and I'm looking to upgrade to a RNS 510 unit.

I've been looking on eBay, but the place is awash with units all of differing model numbers. So if anyone can help with a couple of questions, that would be great!

Firstly, should I be looking at specific firmware and letter prefix on the model number for my year? I've heard of battery drain, but not sure which models it relates to?

My car has bluetooth, and DAB. Will both of these still function with the new unit?

Here are a few I've been looking at I have been looking at:

http://www.ebay.co.uk/itm/NEW-VW-RNS-51 ... SwnDxUgib4

http://www.ebay.co.uk/itm/VW-RNS-510-LE ... SwA4dWJrOu

http://www.ebay.co.uk/itm/VW-RNS-510-HD ... Sw5ZBWJrDw

Any help or advice massively appreciated.