5.3L towing

[Chuck Gallagher]

Tony;
I'm guessing your 5.3L truck wasn't originally assembled with the trailer towing option which my similar 4 door Silverado does have.
Mine is rated to tow an 8500# trailer. It pulls my 7500# loaded Sooner 24' fine up any hill. When I go up long steep hills I put the trans in 2nd gear and set the cruise at 52 MPH. That keeps the engine under 4000 RPM.
If I owned your truck I would do the following.
Change the axle ratio to either 3:73 or better yet 4:10. Be sure to fill the axle with full synthetic gear lube. Go to the shortest tire your wheels will mount and within your rated load spec.
Put a temp gauge on the trans and don't let it get over 220 degrees. If it does you need more cooler. Use nothing but the best full synthetic engine oil and change it and the filter often.
If your truck is a 4 wheel drive ignore all of the above and trade it for a truck with the trailer towing option.
I can not recommend any changes to the engine.
Hope this helps. Good luck.
Chuck