Hi All. New to the board and diesel ownership and I'm counting on the vast knowledge of the collective to point me in the right direction.

I drive a 99 3500 5.9L 6-speed. On acceleration in 6th gear at about 60 mph Friday night it bucked and lurched and immediately started grinding. I got it out of gear pretty fast and coasted to a stop, but the damage is done, whatever it is. The clutch feels pretty normal, maybe a little less pedal effort required, the transmission will easily move into all 6 gears and reverse, but grinds and the truck only wants to move forward a little.

I've driven a number of manual trans vehicles in my lifetime and had various things go wrong, but I've never seen anything quite like this. I know it's hard to diagnose from my description, but what went bad? What do I need to know about the particulars of this truck? I'd like to be armed with some knowledge when I take it in. Thanks in advance for your input.

 

is it a 4x4? is the engine modded? need more info on the truck could be rear end transfer case drive line or axle stripped

 

Yeah - I didn't think of those little details. It's 2WD and as far as I know dead stock except I had a Fass DDR lift pump installed along with a new VP44 in August. Really improved performance and fuel consumption. I thought of the rear end possibility, but it sure sounds like the noise is in the transmission area.

 

well jack you truck up and start grabbing shafts, checking joints shafts, cracks, put everything in neutral and turn the shafts and listen and feel.

 

Was it a 6 speed from the factory? My dads 99 was orginally a 5 speed.

 

If the truck will not move any direction in any gear then possibly something in the clutch assembly is broke or the input shaft is either stripped or broke. No matter, if you've already got under there and looked for any obvious problems but found nothing then its obviously internal and you're going to have to pull the tranny. The early 6 speeds have a smaller input shaft than the 2000's on up and I remember reading that the early 6 speeds can have 6th gear problems. Not sure what the problems were but no matter. Maybe contacting a large transmission shop like http://www.standardtransmission.com/

 

6 speed Not an option in a 99 truck.

 

Yes it was. It just wasn't upgraded to a larger input shaft and different clutch until the HO's came out.

 

While the engine is running or shut off it will easily go into gear?

 

If it was a 5 to 6 speed conversion it will have a larger clutch with the smaller input. My dad and I both had the swap done and center portion of the clutch come apart on our first clutch.