I've got a 2004 ba one tonner, its just a 6. Now my problem is, its done 135k on the clock, but ive been though 2 gearboxes, ( soon to be 3 ) and its been in to fix the diff 4 times. Now at work i carry about 300kg in the back, and also a trailer with alot of weight on that aswell. About 400kg on average. Is they anything available made to cope with this sort of weight? I know common sense would be to get a 4x4 or something like that, but in my line of work that doesnt work... Also the trailer isnt your standard trailer, its like 5 meters long, and the cars an auto btw.

So ummm yeah, any ideas?
Would be much appreitiated, im losing alot of days at work with car problems.

Does it have a transmission cooler?

Biggest killer of autos is heat, so fitting an aux. cooler is a great investment into the longevity of your gearbox.

Buy an E series.

Not really all that helpful!

A mate of mine has had a BA and now has a BF ute, tows a huge trailer around all day with garage doors on it. The ute has two large tool boxes on it so is carrying a similar if not more weight. He's never had a problem with either his diff or trans.

@Sheow, when you say you've replaced transmissions, were these new or secondhand or rebuilt.
A mate of mine is a trans specialist he swear by the AU box as being the best, something to do with the pump being stronger/better design. Apparently the BA-BF pump was changed to make the box quieter and more fuel efficient. He rebuilds lots of taxi boxes using AU pumps, once rebuilt they last for hundreds of thousand km's.
As you are towing, and as already mentioned, fit a external trans cooler, a big one if you haven't already.

actually its the eb/ le91 that is probably the strongest of the btrs, larger pump, wider gears ect, all the later boxes have the smaller pumps and narrower gears to help with noise reduction and internal weight saving, meaning less drag for a more efficient and ecinomical vehicle..
most decent rebuilt auto's are usually fitted with the le91's larger pump. due to the later le93 onwards pumps stripping the splines..
eg,most taxi packs and police cars were are usually fitted with the larger pumps when rebuilt..

Only going on what my mate told me when he rebuilt mine