As per the title, the Alabeo Cessna C441 Conquest II is now V4 compatible, with a suitable installer available (which is updated on Just Flight incidentally if you bought it from there as I did). It's still as bonkers as it ever was with still a lot of stuff not fixed (thanks to the legendary crapness of Carenado/Alabeo when it comes to sorting stuff out), so if you have the FlySimWare one, you'll be waiting for that one to be V4 compatible instead, as I am am lol, but in the meantime, if you have the Alabeo one and want a C441 in P3D V4, it's (just about) better than nothing.
So, it still has all the unintentionally comedic typos in the cockpit like it had from day one, despite this supposedly being version 1.3, i.e. it apparently has an 'Ignition Overdrive' on its engine panel instead of it being the Ignition Override of the real Cessna 441 lol, and is evidently equipped with Fire Extinguisher 'Bootles', which I expect will be handy if you're ever on Merseyside. Oh, and it still sets off like a top fuel dragster when you dare to even touch the throttles whilst taxying it, so christ knows what they've patched in two updates if it still has all those stupid errors, but it does at least install in P3D V4 now.
I have managed some flights in it, so it's not unusable by any stretch, but I do wish they'd sort it out a bit.