Distributor Oil Leak..."call me crazy"

OK the results are in. I put the van dist in the Duster and ran the car for close to 2 hours with no leak at all. Unfortunately the Duster dist, when run in the van, did not leak so I can't positively blame the dist exclusively for this. Maybe it's a combination of the dist being a little messed-up along with whatever else may be going on in the engine like oil pressure or even the way the oil splashes around in there.
I'm gonna look for another dist for the Duster and hope it works OK. The van dist has a different "collar" than the duster and also less play in the shaft. The collar has a flange on it that could be blocking the oil from getting up in there. I suspected when I saw it that this might solve the problem. Duster does not have this flange. Van dist with flange is like the inset one in the photo. What an irritating little problem. Got several hours and prolly close to 100 dollars in fuel into this thing, but thankfully I'm pretty-sure this is the last of a series of difficult fluid leaks on this newly assembled car (none of the others are related to this) Thanks for everyone's help and input.
BTW that friggin' '79 Dodge Van I've had since 1987 is still the best vehicle I have ever had.