Hello All,
Recently joined the ranks of the Mopar family, suspect an issue with the drive train. Would appreciate any help.

Problem: After a cold start, I release the emergency brake and put the manual trans into reverse. Truck backs up under power for about 5 to 8 feet and then halts hard almost like I hit something. Truck rocks forward and then settles like the brake is on. I don't try to force it to back up. I take it out of gear, put it in 1st and go forward. The second time I put it in reverse it works without issue.
I seem to only have this issue after stopping the truck and putting on the emergency brake. Don't think the brake is hanging as I am able to press the clutch and let the truck roll down the driveway.

A little background.
Recently (10/22) purchased a 2005 Dodge Ram 1500 ST Reg Cab 3.7L. Newly rebuilt motor, new clutch. Noticed some oil on the 9.25 dif around the pinion seal and up on fuel tank. Previous owner (single owner) said they never serviced the differential and it had 155,000 miles. I have put less than 300 miles on the truck. Noticed a vibration when I press the throttle and when I let off the throttle (possible u-joint failing), vibration seems to go away with constant throttle on the highway for example. On the last drive noticed a squeak from the rear end at low speed that turned into a squeal that is barely audible at speed.

Truck sat unused from 2/22 to approx 10/22, when the motor was replaced. There were drag marks from where the mechanic pulled the truck out of its parking space. He claimed he had to remove the drive shaft to get it into the bay (I assume the wheels were rusted). No indication that yoke was marked prior to removal.

Purchased differential cover seal, pinion seal, new pinion nut (as there was a recall on original), new heavy duty (non serviceable) U-joints. and 3 quarts of Synthetic SAE 75W-140, just waiting for non-sub-zero temps to put it all in.

My concern is that the differential could be damaged after so long without service. Not sure if the reverse issue is a transmission issue, differential, or something else all together.

Any Ideas would be greatly appreciated.

 

There's been a lot of work done on your truck, hard to tell if your problem is result of poor maintenance or not.
I think first places I'd check are the differential fluid level and brake calipers. The diff fluid should be about 1/4 inch below the fill hole, when on level ground. I suspect your diff is very low on gear oil.
If all looks ok, consider replicating the problem; back the truck up until you feel the lockup coming on then stop. Open the diff and do a visual inspection. Put the rear on jack stands and rotate the tires by hand and watch what happens.

 

Is the E-brake on that drum-in-hat? If so, I would have a look at the shoes.

 

Yes, it is drum in hat. I will take a look at that. Thank you.

 

That makes sense. I was planning on doing the maintenance but I hadn't considered replicating the issue and then opening the diff. Thanks for the advice.

 

I rec against driving the truck again until you have good gear oil level.
Do you have open diff, or anti-spin (aka LSD, posi-trac)?