doh ive got a 700. the 203 has 27spline, not sure on the 300 outputs. he says:
Changing drive train and projects so my doubler is up for sale. It includes the TH350 to NP203 factory adapter, NP203 with the custom output shaft, cleaned and painted, great shape, clocked upside down for flat skid. The Doubler adapter is also inlcuded made so the Dana 300 is clocked perfectly flat, both are cleaned and painted recently in great shape. They have very little use on them and worked great!
$700