I`d definatly sell privately.
After all most dealers won`t offer much for a `leaky Lunar`. I know, I had one, as well as a `leaky Mardon`,a `leaky ABI` a `leaky Eccles` a `leaky Abbey`, er, well actually they`ve all been `leaky` although the dealers never actually saw any of the vans.....
Of course, the models I were interested in were exemplary in their construction unlike the things I were trying to foist upon the poor dealers.
A decent van will command a decent price and it should be to your benefit not a dealer whose only concern is is profit margin.
Just make sure the money is in your hand before you part company, there are a lot of scams out there.