which u-haul is better to tow ?
 

5' x 8' trailer:
- empty weight, 900 pounds
- two-wheels, no surge brakes


5' x 10' trailer:
- empty weight, 1250 pounds
- four-wheels, + automatic hydraulic surge brake



being towed about 900 miles distance by a '01 4Runner SR5 automatic w/tranny cooler...

just wondering which would be "easier" on the engine overall -- the heavier trailer + surge brake OR the lighter trailer w/o surge brakes?

Well, easier on the engine would be the lighter weight version, but easier on your brake system would be the auto surge brake version.
Truthfully, your truck should do fine with either one (assuming the same amount of stuff loaded into each). The 350 lb difference isn't much considering the weight of everething else you'll be loading into it.
That said, I'd go for the larger one. Less chance for the trailer to push you farther than you want to go.
Just make sure you're not overloading the carrying capasity of your truck.

I used a U-Haul trailor similar to the 5x8 you list last weekend (actually, it was a 5x9). I loaded it up with about 150lbs of brush and other junk I was taking to the landfill. I couldn't tell it was back there when stopping and only barely noticed it when starting off from a full stop (I have a 5spd 3.4L).

Chris

I had no problems with the 6x12 so I'd just say to take the larger of the two for the better braking system.


http://www.top4runners.com/ja/extra/uhaul1.jpg

Had the same setup as pictured above (even the same color!) when I helped afriend move to Colorado from Virginia. Had no problems towing, but kept speed to around 60 MPH for safety reasons.

The best advice that I can give is go for the bigger one (you might need the space and the brakes cant hurt) I moved about 1600 miles with a 6x12 without too many problems, just make sure the front is heaver than the rear of the trailer - it will give you control problems!!!

If my 3.slow with an AT could climb out of San Diego without any problems your 3.4 sould be ok.