Leak at pinion splines

Hello
I recently installed a Dr Diff 3:55 gear set into the 742 carrier in the 68 Barracuda.
Noticed a re occurring teaspoon size puddle of oil on the garage floor.
Last evening I put the rear end up on jack stands to investigate.
From the circular oil spray on the under body the leak is definitely at the pinion seal end.

Removed the retaining bolt and with light hand pressure was able to pull the yoke from the pinion shaft. Noticed that the inner seal of the pinion seal and the OD of the pinion seal from 9:00 to 3:00 was absolutely dry.

Took the same yoke and attempted to seat it on the OE pinion that I had removed from the differential. It would only partially engage. That same yoke easily fully engages on to the new Dr Diff pinion.

It is apparent that the oil leak is due to the loose fit of the pinion splines to the yoke with the new gear set. I contacted Dr Diff and he recommended putting RTV on the splines make a seal.

I had previously did some internet research and I found that fix mentioned in a couple of other forums. GM and Jeep stuff.

Does anyone else here have experience with using RTV to seal the pinion splines?
I am thinking it would be best to coat the splines in the yoke with RTV then press it on so the RTV gets squeezed out. Putting the RTV on the pinion shaft splines would extrude the excess RTV into the differential, I think.

thoughts on this?