My drive shaft broke half at the weld. It is no longer attached to the transmission. This happened while my teenage son was driving it. When he put the truck in gear ( Before he realized what happened)it made a loud grinding noise. Does this mean the transmission is damaged?

 

Not necessarily.

Is it 4x4 and if so, which driveshaft? If the rear is damaged, try shifting it into 4x4 (key on engine off, then start it) and see if the truck moves - you don’t have to go far - you’re just testing to see if the transmission still engages.

Part of proper operation when shifting into/out of gear is the brakes being applied, which holds the driveshaft and prevents the transmission output shaft from rotating until the pedal is released. Without that, the transmission output shaft will start to rotate as soon as the clutch pack is supplied with adequate pressure.

The grinding is most likely the result of the rotation as the clutches were engaging, but the transmission can withstand this type of thing to a certain extent.

You’re probably going to have to get a new driveshaft in it before the transmission can be properly assessed.

 

Wow. For a drive shaft to break like that, must have been something stressful going on.... like maybe your son changing gears between forward and reverse while moving, and he hasn't confessed to that yet? When I was young and stupid I remember shifting to drive and flooring it while rolling backwards so that I could spin the tires and burn some rubber...

Swapping a drive shaft out isn't rocket science, and I've done it myself on at least one car, as the original driveshaft was damaged and vibrating, and I couldn't get anyone local to balance the driveshaft, so I ended up replacing it. Once that is replaces, you can assess the transmission and differential.