Mutual give into me

Mutualism influenced Marxism 

Includes these Mutualistic views on private property 

Mutualists argue for conditional titles to land, whose ownership is legitimate only so long as it remains in use or occupation (which Proudhon called possession), a type of private property with strong abandonment criteria.

Dark Mutualism is connected with Marxism (and is more pro private property than regular Mutualism: "This transition from Proudhon and Carson to classic Marx certainly has yet to be properly articulated. I know that Edmund Berger is itching to write a book rehabilitating Marx's critique of Proudhon from, well, rehabilitations like that of Iain Mckay which he only finds half-convincing. This should clarify quite a few things about the accelerationism/anarchism relationship, I hope."

I don’t disagree. So much of the proudhonian corpus is still unexplored to this day, especially compared to the marxian one, that I tend to feel insecure when it comes to making big absolutist (ha!) declarations about what Proudhon has forgotten to take into account in his thinking, or whatever.

From what I can see, cyborg_nomade takes Proudhon’s great anti-absolutist manifesto to be his Philosophie du progrès which, while a great text, is not exactly fully representative of Proudhon’s more mature work, I think.

Nonetheless, it does seem to me that Kant’s influence on Marx is much bigger than it is on Proudhon as it comes to their respective approach to both political economy and capitalism. But, to go in the direction of what you are saying, it is after all in the Grundrisse that Marx’s kantianism is at its most glaring—that is to say, in unpublished manuscripts—so who knows what you could find in Proudhon’s own! I’d be delighted to find stuff on that.