I'm not sure if this will work, but you can give it a try.
Check in to
Your Profile > Select B-52 Driver > Extended Download Service > Get New Links.
Now before you download it, check the name of the file (by doing a mouse over the
Server 1 (USA) download link). If the file is named
csb521_1000.exe, then it is the full CS B-52 Driver (you won't need the original csb52
0_1000.exe). But if it is named
csu521_1000.exe, then it is the upgrade version and you do need the original csb520_1000.exe file.
I bought the B-52 BUFF Exterior and then the B-52 Driver Upgrade, when the B-52 Driver was released, but I ran into install trouble and so I needed to get a new link to download the B-52 Driver Upgrade, but instead of that getting that (cs
u521_1000.exe), I found that I gotten the B-52 Driver FULL version (cs
b521_1000.exe) and so I just install that now. It is much easier than installing the exterior followed by the upgrade.
Hope this helps.
Mark