well... by my experience a progressive spring fits both a swinger & a dhx, so by extrapolation i would conjecture that a swinger spring fits a dhx. though i have no actual empirical evidence to support that theorem (which is why it remains a postulation and not a statement of fact).
I got a Swinger spring to fit on a Vanilla RC. The spring is a little larger in OD though and comes very close to the reservoir. So far so good, but I haven't put any time riding on it other than the parking lot test.