To connect only to a PC, I'd recommend
Ultimarc's A-PAC or
U-HIDThe primary difference between them as far as your purposes are concerned is that the U-HID will need to be connected to a PC and configured for potentiometers before hooking it up, while the A-PAC is already set up. There are other differences, but I don't think any are relevant to your application.
These won't work with an xbox360 though.
Ultimarc is coming out with a new interface that is compatible with xbox360. BUT since the products it is replacing don't have analog inputs, I assume the new one won't either.
http://forum.arcadecontrols.com/index.php/topic,142969.msg1482378.html#msg1482378It may be worth shooting Andy at Ultimarc an email to ask if analog input will be an option.
I've tried hacking 5k arcade pots to xbox360 controllers before. I found the movement to be "clunky" if using pots less than 10k.
The cursor will move in small jumps instead of being a smooth motion. Both 10k and 100k pots worked fine.
You can read about my trials and tribulations of analog xbox360 controller hacking here:
http://forum.arcadecontrols.com/index.php/topic,128941.0.htmlThe big issue with swapping standard pots in place of arcade pots is that sometimes the arcade pots have less rotation (deflection).
You only have to turn them say...90 degrees to go from 0-5k whereas a standard off the shelf linear pot would need to be moved 270 degrees.
I know this is the case with analog arcade joyticks/triggersticks. I do not know about the ones in your ManxTT cab.
The standard pots can still be used on a PC as long as the game allows for calibration, but on a real xbox360 you don't have that option.
The pots will work as long as they're centered properly, but you might run out of physical rotation in your handle before the pot is rotated enough to post the full 10k.
This may mean that you can't hit full speed or turn all the way in some games.
If it were me, I'd use the A-PAC and settle for just having PC games.
If pursuing the xbox360 hack, the first thing I would do is measure what range of resistance the pot is delivering (0-3k, 0-5k) and how many degrees of rotation is required to get that range.
(even though they're 5k pots, physical stops might prevent them from using their full range)
That should tell you whether you can swap in $3 pots from radioshack or whether you'd have to fork over a small fortune for 100k happ pots.
There's also the route of having an arduino or some other microcontroller take input from the 5k pots and send a corresponding correct output to a hacked xbox360 controller, but that's way out of my realm.