Need advice and direction with a complete engine replacement

[zedzeppelin]

I have a 2002 LR RR HSE 4.6 VIN#SALPM16422SA465761 and I am in need of a replacement engine. As a total noob, I am completley in the dark on this however, I have come to understand that the 7th digit in my VIN number is very important to know which engine to purchase as a replacement.

As I understand it, there were 6 engines for this vehicle and it depends upon 2 seperate things:
1. If it is with or without secondary air injection
2. If it was manufactured in the US or Canada

Apparently, the 7th digit of the VIN is suppose to tell you this info. However, my 7th digit is a 6 and know one knows what this means. Now with that said, I believe my engine is a UK built engine and that is why it explains the 6 as my 7th digit.

So my question is, since this is a British built engine, where can I get a replacement engine for this vehicle?

Thanks in advance,
Zed