Both the 1820 and 1820m connect to a full height PCI card inside the PC using a few cable. I used a flex PCI adapater to fit mine in (on its side). I have the 1820M relocated to an easily accessible spot in the boot

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Price wise, I got my 1820M for about $750 AUS.
I have an 1820 (non M - which is 95% as good as the M version [ M version has slightly higher specs and has an additional pci card that you will never use) which I am thinking of selling.
PM me for me info.