Depends on tyres. TH400 with 2.78 are great, just has to be the right engine ie tow cam in a 308 or a 350ci Holden or Chev engine. My old HJ ute was a 350, TH400 and 2.78 LSD. It was great, good highway cruiser, towed well and was still quicker than a stock 308 4spd HZ ute over the quarter. I changed it to a 3.08 diff later as I was worried about busting the LSD and it made bugger all difference, just 10% higher revs.