Looks like I've had more success with my 235. I've got a 3/4 ton GMC (1952) with SM420 and 4.56 rear end. I put a class 5 hitch on it and towed a U-haul flatbed trailer at a mile in altitude over dirt roads with a lot of washboard with a 2000 pound, engineless car on top. On the hills, I'd slow to 50, on the straights, I'd speed up to 60, so overall, I was able to average 55 in those rough conditions.
I don't think the 235 is capable of very serious towing either, but I was pleasantly surprised by how well it handled the U-haul car hauler.
