Mine's too big for a single axle too, but that's how they did it back in '48. I have a 7500 lb axle on this one. My 2003 Yukon XL 2500 with the 8.1 and 4.10 gears gets about 8-9 mpg towing. Not much better without the trailer, but that's what I got it for anyway. It sure pulls nice!