had the tranny 46re on '99 1500 4x4 rebuilt in Dec. noticed that on cooler mornings it groans in reverse when cold, goes away when warmed up. Also notice a sharp/hard shift to reverse when warmed up. I saw the TSBs on this.....question is, if I leave it alone will it self destruct from this..........everything else appears fine.

 

Reverse is known to have a "growl" when cold.
It gets alot of pressure to the apply servo, more than any other hydraulic part.
The growl is nothing more than the pressure regulator.
Its just the nature of the beast. I always start mine and immediately put it into neutral since the oil circulates at a higher volume than in park.
As far as the rough apply, your high gear(3RD) clutch pack is half of your reverse.(don't rack your brain trying to figure out how,it just is!)
If they used a shift kit or such, it will use more pressure to apply these clutches.Firmer shifts=less slippage=longer life of the clutch pack.

 

On a cold start you need to start the truck, put the tranny in Neutral and let it run for 20-30 seconds or so to let the fluid circulate and get the bubbles out that may have formed as the fluid drains down. This should help your problem.