I have 3 (yes, three - don't ask why) dual quad set-ups, but none are for sale at the moment. I have already promised one, and the other two are slated for use on two of my cars.
I'm willing to offer free advice on setting up a 2x4, but remember - you get what you pay for!
Also, about that offset ... the pinion angle is already set by the design of the driveline. Offsetting the engine another 1/2 degree will not affect the performance or the longevity of the drive line. The U-joints don't really care where the angle comes from - they just allow it to happen.
