Here is an interesting quote.
35 spline would be a strength downgrade from the factory 14-bolt 30 spline layout, so I'd be surprised if anybody will be offering them as a standard-production item.
Personally, I think if I had to have that, I'd make it out of a set of D60 side gears, a stock 14-bolt carrier, some tube scraps, and a bunch of welding wire.