'Dallas' Star Larry Hagman -- R.I.P. ... But Only After You Pay Up

Legendary actor and "Dallas" star Larry Hagman broke his word by dying ... and now a guy who says he was left high and dry wants the ghost of Larry to ante up.

John Castonia claims he was lured from Texas to Cali in 2012, to manage Hagman's career as he shot the "Dallas" remake for TNT. But John was no fool ... he says he got a 7-month guarantee in his contract -- $2,500 a week.

Here's the problem. Larry died 3 months into the deal, and the money train stopped. So now he's suing Larry's estate for the remaining $42,500.

The Ewings might handle this differently.