Noise from transmission?

I have a 2007 with 400,000 miles. Probably near the end of life, but here goes. Still averaging 40 mpg, lots of highway miles. Timing chain probably needs replacing. I had it at the dealership and they want over 4 grand for a used motor. She runs just fine except for the P0011 and P0037 codes that pop up occasionally. Recently changed the VVT valve, cam and crank sensors. Now I’m getting noise from the tranny on acceleration and when I maintain 55 mph. Sounds like valve taps but it’s not. I noticed that I’m using more volts to run at speed. When at 55, discharge is at a constant 7-14 volts until after 3-4 miles constant speed, all of a sudden it starts charging at a rate of 4-9 volts and the noise gets much louder. On deceleration, charge rate goes to 12-18 volts. Braking, 20-36 volts. I’ve maintained my battery from day one, because I have a partial HV battery sitting here for just replacing packs. Any ideas or just give up…. Thanks!

 

uh… yes amps. I misspoke or mis-typed. My mind was saying amps but my fingers said volts. Basically, it discharges at highway speed, and charges like I just threw a switch. But only for about 3-4 miles, then discharges for a few miles. Never acted this way before. And as I said, noise is louder during the discharge.