Nope. Gas destroys diesel engines. If OP didn't start the truck then it's only like a $300 fix. If he did... Then he's totally ******. Diesel into gas engines doesn't totally ruin them though

Going to assume you didn't know not to drive the truck after. There is hope if home is not far away however. Get a mechanic out asap to drain the lines and replace the filter. Hope all goes well and it doesn't cost thousands to fix.

#6 you are mistaken. Gas will **** up a Diesel engine. Diesel will not harm a gas truck that bad.

Yeah it's all about the chemical composition and stuff. Either way your screwed unless a siphon is possible. Better luck next time OP

An honest mistake has been made .I did the exact same thing to my best friends car. That was a gong show but we got the tank drained before the car was started.. I hope you didn't drive it that way.. I really feel for you OP.

I understand that you attempted to do something nice, but I hope you don't expect your brother to pay for your mistake.

I really hope you haven't started it yet. Best thing to do is siphon it back out and save it in cans for later... If by too late you mean you already started it, then I sincerely hope your brother is a forgiving person.

I moderated this

Could you conveniently recall a long-repressed brotherly hatred just for the occasion?

If you drove it, you would've noticed if it is a diesel, usually by waiting for the lights on the dashboard to go out before trying to start the engine. Sometimes they're nice enough to put stuff on the fuel caps to say it's diesel. Or that could just be the cars I have driven and seen others fill up. But hopefully you were able to remove the fuel before driving on it.