Worn Tranny Causing Vibration?
 

I have recently noticed that my truck is shaking worse and worse between 65-75 mph. This face is what my head looks like while on the interstate [verymad] I especially notice that the column shifter shakes more than anything else in the truck (annoying). I thought that my BFG's were due for a rotation and balance, so I got that done today. No Change! I asked the guy at the shop how bad they were and he said they were already close to balanced, he just had to fine tune. I guess that rules out an out of round tire.

Is it possible that my worn out POS tranny could be causing this? I have heard that overdrive is the first thing to really go before the rest of the tranny implodes. Is this true? One of the reasons I got the triple disc was for this problem when it was less noticeable. It didn't seem to affect the shake. :confused:

Is there anything else out there that I should check/fix as well? Thanks in advance for any help.

The PCM maybe? I have a 94, and it shudders between 42 and 48. After lots of searching, I found a service bulletin from Dodge that at 1100 RPMS and around 42-48 miles per hour, there is a shudder. The fix is a different PCM. According to the bulletin, it applies to 94 and 95 Cummins Dodges with autos.
The service bulletin # is 21-04-05, dated April 14, 1995.

Interesting...I'll certainly check into that. Do they still honor the bulletin now?

I turned off OD and got on the highway this morning to see if anything changed. It was a little smoother, but certainly not the entire problem. I'm wondering if the hanger bearing might be playing a role. Maybe when I get my Goerend installed I'll get them to change the bearing too.