Well, didn't think it'd be so easy...
Let me first say that a part of the motivation came from the price of tyres for the 20" truck wheels, and the fact that I hate Chinese tyres, they seem to be the only brand available in the correct sizes. There roughly $300 each then there's fitting, so around $1280.
My aim was to fit up a better diff than the 3 trillion ton stock one, with easily sourced parts and so on. Bought the diff for $250 with the tailshaft, it's a single spinner.
LN87 Diff from a 2wd, drum brakes. These are a nice HD diff that can easily be upgraded to limited slip, or better still air lockers are easily sourced being from a Hilux. Never mind strength, plenty of the drag racing fraternity are pushing 500hp through modified Hilux diffs.
The easy part? The diff is a near perfect fit width wise, almost identical dimensions to the standard diff, spring perch spacing is about 5mm narrower than the standard, track is about 10mm wider and it has about a 70mm offset to the driverís side. The perch spacing is really only important for strength as I changed them, but you want the perches as close to the outside of the diff as possible for load bearing.
The pinion location is roughly 80mm shorter than stock, seeing as how the stock tailshaft has to be modified anyway to fit up the diff it's a matter of dropping both the Hilux and Ford tailshafts to my tailshaft guy and he'll replace the tube with the correct length and fit the Hilux flange to it.
The Ford tailshaft is 63.5mm in diameter and the Hilux one is 65mm so it'll be nice and tidy.
Only modifications I have made were removing the old spring perches and welding a new set on ($25 for the parts) to the TOP of the diff as I'm hanging it under the springs, same as standard.
No need to replace the standard Ford springs, the Hilux diff bolts up with normal U bolts, only a temporary fit up for alignment etc as I'm in the process of making up a set of adaptors so I can use the massive stock Ford U bolt bottom plate.
The axle tubes on the stock diff are huge so the adaptors really just reduce the clamping diamater, at this point I'll be having some alloy ones machined up, make a circle, make a big hole in the middle, cut it in half and bob's your uncle, all done!
Brakes are simple, the stock brake line comes off my chassis on the left and the hilux distribution block is on the right, I simply reversed the steel lines on the diff (with little bending and no new parts), and made up a braided line from the chassis to the diff (I used braided as I have some in the garage along with fittings).
Glory be to the truck handbrake being a tranny brake, just remove the Hilux handbrake cables and feeders in the backing plates and made a small blank off plate.
Thatís pretty much it, aside from the waiting on parts it's a job that can be done in half a day.
As for the front, well these damn trucks have odd sized spindles and no one makes a spindle kit / disk kit for them it would seem, so I'll do some measuring and make up some bearing adaptors myself and run some 11" disks. Making the calliper mounts up is pretty simple, make a pattern and off we go.
Diff and tailshaft $250
Spring saddles $25
Brake line $30 (assumed, I made one at no cost)
lower clamp adaptors $120 (assumed, but based on experience)
tailshaft modification $250
Total for the rear $675
Haven't started the front yet, but I doubt it'll be more than $300 all up.
Out of the $1280 for tyres alone I'll have $305 left over, easily enough for some second had wheels and tyres. One could do it cheaper by just using normal diff u bolts and not making the adaptors, but those massive clamping plates look cool