1970 FJ40 build (front axle question)

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Aug 10, 2011
Los Angeles
It's been awhile since I posted here on MUD especially since I've sold my 80 a few years back. I picked up 65' FJ40 back in 2015. But had to sell her since I lost my son later that year and then got evicted by my own family member and lost my house all with 3-4 months after my son passed away. Anyways, I recently picked up a 1970' FJ40 and planned on restoring her. I've decided that I'm going ditch the stock front and rear axles. I been reading up the early years 40's came with the 10 spline count up front but forget what year was the cut off before Toyota switched over to the 30 splines.

I'm going to be using the FJ80 full floating rears and can't decide if I want to find a 60 front (if my stock 40's 3rd member is 10 spline) and have a custom housing made like that from Diamond or Ruff Stuff. I also read that the 80's outer are bigger and stronger than the 60's. With my build, I decided to use the 2UZ engine and trans that is off the Tundra/Sequoia, but I'm going to ditch the t-case and use the J-shift t-case that from a 2nd Gen Tacoma or 4-Runner. So with the above setup, I would need a driver side drop front axle. I don't mind spending the cash on the front axle, just want to do it once and do it right.

Hopefully, many of you don't think I'm crazy. But I want to keep this project mostly if not all Toyota related parts. Now my question is, assuming my front 3rd member is a 30 spline. Is it silly to get a custom housing made that is a driver side drop, using 80's outer with the manual locking hubs, and throw in a set of Longfields. Basically I just want a front axle that is flipped for a driver side drop diff using 80's outer knuckles with the manual hub.

I appreciate any suggestions or criticism here.
If your front differential is 1970 vintage and oem, it will have a coarse spline pinion. Not 30 spline. With your build plan, you should replace it anyway. It will be a weak link. New gears will be fine spline, I don't recall if it's 30 spline or not.

As to your front axle staying Toyota with driver side drop, the purest way would be to take an FJ60 rear, cut the ends off, flip it, shorten/lengthen the axle tube's as needed to match your rear axle, and weld FJ60 knuckle balls on. There is a thread here somewhere that shows converting a rear into a front that would be very close to this concept. It might have even been right hand drop, I don't recall.

Edit: I just re-read your post. To have 80 knuckles on the front with driver''s drop, you need a custom housing.
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What is your purpose for the rig? The 2uz is a great engine but takes up a lot of real estate under the hood for its size. I would also consider a 5vz motor and if it's not powerful enough put a supercharger or turbo on it. With the small v6 you can move your motor as far forward as possible giving you a longer rear driveshaft. Plus then you won't have the starter in the valley so it's easier to service.
I recall the 80 knuckle balls can be used on a 40 or 60 housing but requires a little machining. You can flip a front axle housing to be driver drop by will need to cut out a new ring gear slot and drill and tap a new axle vent and weld up the old etc. As far as a aftermarket housing a guy at my work ordered a diamond housing, it's about 4 months past the promise date they told him. I would probably go ruff stuff these days. Nothing wrong with using 80s outers with the 9.5" differential, if you get the housing made to front 80 series stock width you can just use off the shelf 80 series front axle shafts without going custom length.
Keep me in mind for the stock parts you take off. I'm local.:)

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