Hello i have a 76 f250 4x4 with a 410 FE and a np435. My truck runs and drives great but yesterday a bad rattling sound started when i was driving ao i pulled over multiple timea to try and see if anything was hanging and nothing seemed out of place. I parked the truck and drove it again later and it got bad. I was slowing down and the truck just started grinding and jumping so bad almost as if a wheel fell off or if the the front wheels couldnt turn. I pulled into a parking lot to get off the road and still nothing i can see. I checked both wheels lugnuts and hubs and nothing seemed wrong. I drove it home because it was very close and it didnt do it. I am scared because i dont know what it is. Does anyone know? I know its not great details but i dont know what to do

 

Could it possibly the parking break locking the front wheels? When i was stuck in the mud about a month and a half ago my parking break stopped working. Randomly it started working again about 4 days ago. It was not on while i was driving but could it have somehow gotten snagged or something? Its something i have been meaning to fix and that would be great if that was the problem. I just dont want to take it to a shop because 1) i dont like others working on my truck unless i absolutely have to, 2) i dont have the money to take a 40 year old truck to a shop with the problem " theres a bad noice and it grinds" because they would have a field day. I am hoping its something i can fix but the fact that i cant figure it out is scaring me. Any advice is much appreciated

 

It's crummy details yer providing .

Git in there and don't just use your eyes.....Start wiggling and prying stuff around to check for something loose or broken like engine mounts and perches, tranny/t-case mounts, steering box, linkages, suspension bolts, etc. Check for missing hardware.

Post your results.

 

Parking brake isn't connected to the front brakes.

Have you tried shifting in/out of 4wd? Locking/unlocking the front hubs?

 

When i started to slow down the front wheels seemed to lock up and i think the grinding noise i heard while it was happening was the driveshaft continuing to spin. It doesnt seem like its something loose. Something locked up the front wheels and thats what made it jump and buck. Im sorry about the details. I should have exained it like this in the first place

 

Could air in the brake lines cause that?

 

Not hardly.

Get under the front axle, grab the U joints and give 'em a shake. Check both sides.

 

You need to take a look at your brake calipers/pads and or bearings. Jack one wheel off the ground take a look at the rotors...they might be warped and or gouged if your pads are bad and or broken. Ive seen some bad stuff on brakes that cause problems like you say. Also try turning/rotating the wheel when its off the ground and see if you hear grinding or if its hard to turn. That could be bearings going out. Like stated before need more info for a better diagnostic.