Every diesel has had its teething problems, My 6.5L turbo diesel suburban will tow quite well, keeping in mind its not a powerstroke or a cummins. The biggest down fall I find on my burban is she will heat up when pulling a long grade if I dont keep up to interstate speed. My Suburban is a 97 so it has all the latest cooling mods that GM did for the 6.5. She really needs an intercooler to cool down that hot air coming from the turbo. Everybody has there favorite diesel, The old 6.5 is one of the cheapest to maintain if you dont need a HD diesel or want a suv with a diesel. I have owned both a cummins, loved the diesel, hated the truck, and an early 7.3L power stroke, loved that one. My perfect set up would be a 2500 Suburban 4x4 with an Allision auto and a 5.9L 12v cummins in it. Any older diesel is better than whats on the market now. You cannot even see the diesel under all the crap under the hood of a new superduty. Way to much electronics on the newest diesels. I remotely mounted the PMD/FSD driver on my 6.5L and its been a very reliable daily driver and light duty towing machine. And she has 199K on the clock and running strong! Keep in mind that the 6.2/6.5L diesels were designed by Detroit Diesel for GM, and were never ment to be a high boosting or high HP diesel engine. Now that AM General has gotten ahold of it, they have turned over block and head casting to Navistar, redesigned the heads, added a lower end girdle and splayed main caps. They now have it safely producing 250hp for the up armored hummers. You can buy them for your truck, they are called the Optimizer 6500. Not a cheap date, but some of us like the classic look of the GM trucks of that era, and the price is no worse than replacing a blown up 7.3L with a new one. Cheers Mike
The DMAX was designed by GM & Isuzu together. GM was looking for a clean sheet design for a V-8 light truck diesel. Yes, Isuzu built it originally, but with GM input at the design stages. I remember reading that GM engineers were in japan working with Isuzu a year before it was in GM trucks. Look at it this way: what other trucks use the Duramax? None. That tells me that Isuzu built this engine with lots of input from GM. If GM had no input, then why would Isuzu build it? No one else uses it. 
