New Venture NV4500 Trans, driving in 5th gear, while towing a horse trailer on level straight road, truck bumped like I ran over something and engine revved up. 5th gear no longer exists. The shifter goes into 5th, but when you let the clutch out... nothing. The rest of the gears worked fine. I was 250 miles from home and drove it the rest of the way with no problem. I have found out that this is not rare, but a common problem with the Cummins turbo-diesel and NV4500 trans combo. I have found MANY posts on several sites about the same problem. Seems that there is a poor engineering situation with the main shaft and 5th gear splines. 5th gear is about 2 inches long, but the main shaft is ONLY splined for about 3/4 of an inch. This causes the gear to "flex" and unscrew the large retaining nut on the main shaft. When this happens, 5th gear just slides back and doesn't engage anymore. I have seen posts where people have driven for many miles before repairing with no ill effects. Dodge has a new locking nut they claim is a fix to the problem, but again, there are many post to the contrary. The best fix, the one that should have been in the trans to begin with, is a fully splined main shaft and gear. The parts are available for less than $300, but to drop the transfer case and trans is too big a job for most. The price for a dealer or repair shop to complete is $1000 and up. WHEN IS THERE GOING TO BE A RECALL ???