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i have a 3.9 AWD box on my ej22 with 25spline front driveshafts. Not sure if it is a turbo L series box or an rs/ej box,probably rs as it does not have an adaptor plate to moter AFAIK.I want to change the 1.19 low to a 1.59 low using parts from a 3.7 Lseries AWD box.
Some pics of the 3.7


First, is it possible to swap the 1.59 low from the 3.7 L into the 25spline AWD?.
If possible ,what parts do i swap?.Is it just the first cog on the input shaft or the transfer shaft cogs as well.I know the first input cog is 19 teeth,first transfer cog is 23,second transfer cog is 19 and second cog on input is 25 giving overall reduction of 1.59 in low.Is it possible to use the 3.7 L synchros on the 3.9 25spline box if they are better condition?
Any advice is appreciated. I would like to swap the parts myself if possible or if needed , find another good 25spline 3.9 AWDbox to put the 1.59 low into prior for less vehicle downtime.

If you have a Liberty case, which I suspect you must if you aren't using an adaptor, then this has been covered in another post in considerable detail. Have a check at some of the older posts in this section. In breif, yes it can be done with a few mods.

An L Series Turbo Box - Full Time or Part time is only 1.19. You will need a standard L Series box to get the 1.59 gear

I had someone swap the 1.59 gear out of a standard L box into my Full Time Turbo L Series Box.

Have a read here.

Gearbox pictured has 1.59 low, the difference is in the 2nd input and transfer cogs, L series 1.59 and 1.19 input shafts are the same.

The detent casing will also have to ground down in the EJ box for the L lo selector to fit.

Just like lego really.

i removed the second input shaft cogs.
now trying to remove the L transfer cogs, have removed circlip but the retaining pins in shaft wont budge.these retain washers either end of the transfer cogs which keep needle bearings located. anyone removed these before?

I remember there was a clever trick to it, can't remember what. Sorry!

split the ej box and swapped the cogs.
seems the L yoke arm needs some trimming as when box is bolted together the lever arm is unmovable.
have removed some of the mound where spring and ballbearing was. also ground off yoke arm near where switch is located.
my bet is the length of yoke on pivot shaft needs to be trimmed either end.

finally have box in ute with 1.59 low range.
had to get some trimmed off length of bore in fork arm and diameter of synchro carrier.
did not risk welding mound onto fork arm to enable indents for positive location.made an external bracket with bolt in long nut to hold spring and ball into indents on small plate welded on cable arm with good results.
very happy with difference to low ratio.looking forward to getting out this winter .
thanks again to Chris for donating the L gearbox

Fair enough for doing these mods above. But to me - 1.59 low isnt low "enough" for me for what I think. It would be great if there was 2.0 low range!
Cheers
AP

It won't fit into the casing, unless you create a new input shaft as well. (possibly.)

1.59 compared to standard 1.19 is triple the effect. that is 59% low as to 19% low.
i have heard of a 1.69 low kit, from qld ?