So stuff doesn't fit right. I'm not horribly surprised really. Toyota changed the FJ40 fairly substantially between 1972 and 1973. They also had a transitional period between 1973 and 1975 where they combined new parts and old parts together before it was all new in 1976. Weird, hey? Combining a '72 and a '76 figured to have some bumps but it's kind of interesting to see what unexpected hiccup pops up. I believe I've sorted through the nonsense and have even come up with a few different avenues for those who are trying to combine an early and a late model Land Cruiser.
My original plan was to use the entire driveline from the '76. The motivation was that the '76 has a good 4 speed transmission that can take me on the highway while the '72 has a 3 speed that will get me run over. The '76 axles are a little stouter and the differentials have a 4.11 gear ratio while the earlier ones had a 3.70. With bigger tires, I would prefer the 4.11. Plans change, however, as facts begin to present themselves.
As the wrecked '76 was being pulled around from the back of the shop, I noticed an interesting phenomenon. One rear wheel was rotating in the opposite direction as the other. I don't claim to be an automotive genius, but I did get an engineering degree - the labors of which have given me the education and background to assess the vehicle as being crapped up. My diagnosis was affirmed as I overheard one of the mechanics make the comment to his pal, "whoa, that things crapped up."
Upon closer inspection, the drive shaft had been jammed into the differential and had snapped off such that half of the pinion gear was inside the differential precisely 90 degrees off of its designed orientation. "Yup, that's crapped up," I thought. Just in case, we took off the differential housing and cover for look-see.
For those of you who may not be familiar with some of the technical jargon I've used thus far, I've included photos of what a "crapped up" differential looks like.
As a rule, it is undesirable to see shiny metal chunks and massive gouges in gears with relatively tight tolerances. This is a good thing to keep in mind regardless of the application...
The decision was made to use the rear axle out of the '72 and everything else from the '76. This required a little creativity. I got 4.56 gears for both differentials and master install kits. I got a locker for the rear differential and I picked up cool flanges from cruiser outfitters in Sandy, UT that fit on the fine spline aftermarket pinion. I was pretty cranked because they have the bolt pattern for both early and late model drive shafts. They make the flanges for the transfercase side too so I'll be able to run my newly ordered drive shafts full time with the ones from the '72 as a freely interchangeable standby.
In a word, bitchin'.
For you Land Cruiser buffs, I found a cool kit at JT Outfitters that allow you to mate the early model transfercase to the 4-speed transmission. It's about $135 and allows you to run the 2.3 low end ratio of the early model instead of the 1.9 of the later ones. I found this kit too late though and, alas, I now have two or three transfercases that I'll be able to squirrel away.
In a nutshell, I'll be using the late model front axle with disc brakes, the late model transmission, transfercase, and drive shafts, and an early model rear axle with the stock drums. All the gearing will be perfect for the large tires and will still allow the truck to be comfortable on the street. I'll have a locker in the rear for taking it off road and, when everything is put together with new seals and gaskets, it will be far less crapped up and, hopefully, all the wheels will roll in the same direction.
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