79series 5th gear

Tony, your vehicle has the R151 gearbox. The shaft that goes into the transfer can break - Toyota will happily sell you a stronger one, if it hasn't been replaced already.

The factory TD 79series has the stronger H150F gearbox and also has a different transfer case. It hasn't had problems. I don't know anything about the logistics of doing a swap, but without doubt, it wouldn't come cheap, and its possible that other modifications such as tailshafts etc may be needed.

I would be surprised if there was any significant difference in fuel consumption between 4th and 5th gear towing.

Thanks for the advise Phil and Troopytracker. I will look into having a stronger shaft fitted.

Thanks Phill and I will be looking at changing to the stronger shaft as it would be very expensive to retrieve a vehicleout bush. A guy I met (Trevor Baker) had his go at 117000kms. and had it repaired at Robson BrOS. in Perth and it cost him about $900 all up which is reasonable considering the gearbox has to come out to do the job.

Our 2005 LC 79 turbo ute has only 200 RPM difference between 4th and 5th so not that much there for serious fuel issue is there?

By two bobs worth.

Barry

Not sure about Toyotas, but with my GU Patrol 4.2TD, the BIG difference between towing in 4th and 5th is the EGT. The manifold temperature when travelling at around 100k/h DROPS by around 100 degrees C if I drop the old girl back to 4th gear after working her at around 2050 revs in 5th. Revs go up to around 2500, but temp DROPS from around 530oC to around 440oC (these temps are very "ball-park" as the actual temp varies considerably depending on head winds, gradient etc).
Just to expand on the matter of gradient.......even a slight uphill section of road will see the EGT rise by 60 to 100 degrees.
My camper trailer weighs around 1200kg and I do drive in 5th gear as long as the EGT gauge tells me that it is sustainable. I also tend to be guided in my gear selection and speed, by keeping an eye on my Boost gauge.
IMHO anybody with a turbo vehicle, especially an aftermarket fitted one or one that has been tweeked, MUST fit the EGT gauge as a minimum and preferrably a boost gauge as well.
My Patrol was a 2000 model that suffered from the 5th gear spline problem and Nissan replaced it at around 80,000klm under warranty, BEFORE it actually collapsed.
My advice is that it is (or should be) okay to tow in 5th gear in the right circumstances. By that I mean that you should drop back to 4th gear as soon as you strike a slight hill or if you are aware there is a head-wind etc. Basically, you should never make the vehicle labour in 5th gear.
Just my opinion and may not be relevant to your Tojo.
Cheers mate
Roachie