Rear end howls when accelerating at high speeds and grinds when I let off the gas

go to the magicmechanic website and send him this--hes the best there is and will rply

HAVE THE FLUID LEVEL IN THE REAR END CHECKED AS WELL AS WHEEL BEARINGS FRONT AND REAR

Yes, differential.

Check your drive shaft U joint bearings.

Have you raised the back of the truck and had someone run the truck in place to verify the source of the noise ?

Rear diff, rear bearing , even tyre noise ...

smokinbiskit......ya..its a truck there isnt cv boots its a solid front axle

Worn differential in the transaxle

The transaxle will have to come out

To work on the diff,the entire trans
will have to be stripped

Usually if there is a howl on acceleration from the rear it's the big pinion bearing,if the howl is on deceleration it's the small pinion bearing.(the pinion shaft with these bearing is the one in the diff that the driveshaft attaches to)

A pinion seal leaks for one or boyh of these reasons. A worn pinion bearing or a driveshaft vibration, Sounds as though you have both. Do not confuse tire howl with gear howl, be sure.The rear end can run 3 to 500.00 if not more. Ck the gear oil in the rearend for metal content. That will tell you alot. The hard shifting is generally from a sticky spool in the trans valve body. Have the trans serviced w/new oil and filter. The new oil often cleans the moving parts of gum and varnish buildup.in the valve body. One more thing, the rear ends take a special oil and additive if it's a limited slip or posi lock. You will have a popping/binding noise when turning if the wrong lube is install. Have your driveshaft aligned and balanced at at driveshaft shop.or you will end up tearing up the tailshaft on the trans. Good Luck