Aftermarket crownwheel and pinion?

Anyone make and sell these suitable for racing? I need around a 3.8:1sih for an 091 6 rib kombi box...
only other option I can see is a 4.1:1 from a caravelle, but I dont know if the pinion is interchangable between gearboxes?

Any idea what they are worth from VW maybe?

Advice? abuse? tips?

Wes will know this one, he has the 4 pinion caravelle diff in his current box. Dont know the ratio though, but AFAIK they are compatible.

I'm sure there is a plethora of choice ex US for diffs.....