[casioqv]

This is one of my favorite subjects!

I do a lot of towing with 7 series, and think they tow really well. Although far from recommended, I've towed a ~7,000 pound trailer from Portland, OR to Seattle, WA with a D24T 760, without any issues; the factory rating of 3,300lbs is definitely doable. I towed a ~5,000lb trailer 1,000 miles when I moved from Portland to Riverside, CA and now I tow my ~3,000lb sailboat all over the place. The sailboat tows easily and effortless, but the heavier loads were due to "emergencies" and required very careful driving.

The most important thing is great fade-free brakes plus good trailer brakes. A strong hitch, rear suspension, and cooling system are a must also.

My recommended upgrades for heavy towing with a D24T:
-Healthy cooling system with audible alarms on temp and coolant level
-Strong electric fan or tropical fan clutch
-PBR Ceramic brake pads
-ATE Blue brake fluid, changed annually
-iPd overload coils and Bilstein HDs in the rear
-A class III hitch (5,000lb+ rating, 2" receiver: might be hard to find)

Upgrading to the 9xx "big brakes" is a pretty good option also and only requires the rotors and caliper bracket (you can actually keep the same calipers).

An automatic with cooling system upgrades really is better for towing, because it can be very hard/impossible to get a heavy trailer moving up a steep hill from a standstill with the manual transmission. The static forward force they're able to generate slipping the clutch in 1st @2400rpm is only a small fraction of what an automatic makes at stall speed in 1st.

I have an extra 7xx class III hitch I may be selling soon...