Comments on a Chevy 1996 gas 3500 4x4 Dually?

I have had both the 7.4 and 5.7 in 2WD Suburbans. The 2 Suburbans with the 5.7 have a combined 630,000+ miles with minimal issues. They pulled my bassboats and campers w/o a hitch. With out towing they got/get 18mpg avg. My last 7.4 got a whopping 7mpg towing my boat to MD on her last trip with me. Sold that. I would imagine the SRW 3500s would get similar mileage. I would jump on another 5.7 in a heartbeat. My current 5.7 has 310,000 and is getting a used heater control set up today. Other than typical, expected, stuff like bearings, rotors, etc it has been a dream. Our 1st 5.7 needed a tranny rebuild at 150,000 and ran great at 320,000 when we sold her. That one had rear heat/ac issues at that point. We bought the 96 in 2004 with 120,000 for $5000 and put a total of 5k more inc the tranny into her. This one is a 96 we bought for $1300 with 240,000 miles. Maybe another 2k into her total inc tires. Pretty good return on our $ if you ask me. I had a 96 3500 crew cab 2WD pick up with the 6.5 that I absolutely loved but the motor hadn't been treated the best before I bought it. Great truck, hauled bassboat and PU TC w/o issues until the motor started going. I would buy another even with the 6.5 as I have learned a lot about tweaking them and caring for them. I currently drive a 96 7.3 PSD 2500 4WD which is a great truck but I was a lot more comfortable in the Chevys.