Holy cow what a difference. I have only had the truck about 6 weeks, and a couple times I loaded it full of firewood at the house to move the wood across the yard. On those occasions I found out what is meant by the term "frowning springs." Just filled up to the bed rail with split oak for a 100 yard trip, the rear sagged badly. Maybe 2.5-3 full inches.
Friday I got the Timbrens on and this weekend I took the truck to the woods. I put exactly the same amount of wood in it as before--stacked, full to the bedrail. It went down about an inch and stopped. I drove it 55 on the highway just because I could, and it handled very very well. For the purpose I had in mind when I bought them, the Timbrens are perfect. I doubt they are a lot of help in every situation we face because of the wifty rear springs on these trucks, but for my issues (occasional fairly heavy hauling short distances, pulling a bass boat long distances) they are the perfect answer.
Now I am thinking about putting a set on my 3/4 ton Dodge Cummins.
I was looking at $4-500 for new rear springs plus paying someone to put them on. I paid $200, including shipping, for these and put them on myself in about an hour for free. Piece of cake.
Once in a while you make the right call, save some money, and get what you need.