I'm fairly confident that the radiator won't fit easily. But then again the LS1 doesn't exactly bolt up but people do it anyways. The Altima radiator is built for a FWD setup, the Altima radiator is wider than the frame rails on the 240, and the hose inlet (bottom) is in a different positions. And there is no sensor on the radiator for water temperature, its on the block.
It is common knowledge that the Altima fans will fit the 240 and its radiator with light modification. I've recently installed the fans to my 240 and have been happy with the results. I'm still in testing and diagnostic mode before I do a writeup. I have it wired using two dual source relays (brown Altima relays). On the ECU side of the relay switch I have spliced a switch going to ground for manual control. I have them wired to both come on in high speed mode, there is no modulation (off or high). I have it wired to maintain as stock as possible behavior; the ECU turns the fans on with the AC (assuming the speed sensor is registering under 12mph.) but after getting close to overheating I quickly came to the realization that it doesn't kick on based on the temperature (which I was under the impression by the FSM that the ECU would turn on the fans.)
Inertiadrt:
The 240 radiator would fit the Altima lower supports but I wouldn't know why you would want to reduce your cooling capacity.
Also you might note that ceniack put the Altima radiator in his 240 but seem cram it in place. And is something I wouldn't recommend. The article he wrote documenting his experience is here:
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