[Mike_The_Grad]

I have prothane polyurethane engine mounts and energy suspension polyurethane trans mount. Those are only about 3 years old and in good shape. I dont run a mechanical fan anymore so no shroud for contact. I run dual electric fans that are mounted in their own shroud.
I had my driveshaft out last year for the trans rebuild. So I took the time to paint the drive shaft satin black just so I could see better for any type of contact. Nothing so far. The center support bearing was replaced at the same time and I special ordered the correct Timken brand support bearing.
I hadn't thought of the torque converter cover yet. It is an after market chrome one. I've already had it come loose on me before and lost a couple of the original screws. I'll take it out today and drive it around.
Yes it sounds like it's coming from the rear but inside the cab it's almost like it happens directly under me. I cant feel it in the seat or steering wheel or floorboard or anywhere for that matter. But it is definitely a sound caused by road conditions. I think the best I can compare it to is if someone hasn't done the brakes in a really long time. Like past the point of saving the rotor and the wear tab indicator has been gone for months. Sad to say people let their brake system go into such disrepair. But I've seen it with my own two eyes and worked on a few over the years.
Wen it happens it doesnt slow do the truck or lug the engine down. If I keep my foot into it the truck accelerates but so does the sound. It's not at engine rpms. It's at vehicle speed. It stays a constant volume though but will be at a faster rate if I'm going faster. It seems to be happening more frequently and even little variations in road conditions seems to make the noise happen. I figure it will show itself sooner or later. I just hope it's not something serious. Or expensive...lol.
As to the caltracs, I was running them with a piece of heater hose over the contact bars and had them adjusted just until they touched the heater hose. But after a few days the heater hose would be cut through and disappear. So I started running them where the contact bars would just touch then back them off a half turn and lock em in. But I was getting a really bouncy ride because of the extra travel. So last weekend I adjusted them until they just touched the leaf springs and locked them in. Basically zero preload. Ride stiffened up but made no difference in the noise I'm experiencing. Thank you guys for the suggestions and help. I will keep this post updated as I try and figure it out or something changes.