Differences in 3rd members by year

[archie73]

Bit of bench building here and the cart is way ahead of the horse, but I’m killing time…

I have a ‘67 basket case build in the wings and I assume it has the dreaded ball and claw/9mm brake fitting axles. So not exactly a good recipe for larger tires.

Current plan is to use 80 width axles, so different housings. I have a spare ‘73 pumpkin in good shape to start the build. What about the ‘67 thirds? Are there any strength differences over the years? I know the rear fzj80 has a fine spline pinion and the 100 series has a load bolt(?). Are all the 40 series chunks the same?

 

[GRM]

The castings on the diffs get better as they get newer. 80 series, 100 series, 200 series and Tundra diffs are significantly stringer than early diffs. I’ve seen those early diffs break apart (housing shattered) from heavy off-road use.

If you are planning to wheel it, I recommend starting with a 1991 or newer 9.5” housing.

 

[Living in the Past]

Are you restoring a FJ40 with upgrades or building a rock buggy? Those are two different vehicles. Unless your planning a lot of horse power or heavy rock crawling would search 1/78-1/79 axles from a US FJ40. Those are still 4.11:1 have a fine spline pinion and disc brake front axle. Those will bolt directly in. Disc brakes regardless axle will require upgrade to brake system from 67. Never considered 40 series axle weak. Especially compared to jeep and scout axles from the same time period.

 

[sandsfj40]

In 1979 they went to 3:70 with the fine spline, so be careful. I just swapped mine up to match the 1966 rearend at 4:11.