1987 FF dually rear into a 1978 Toyota Chinook

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I've read on several Toyota forums including this one - that the center section on the FF axle is the same as the 1/2 ton axle. NOPE. Mabye for a later truck but not on a 1978. I just found out the hard way. Seems Toyota trucks went through a major change between 1978 and 1979. Two very different trucks. Something I had not anticipated. Maybe Toyota was gearing up to introduce 4WD and thus the radical changes.

First thing I noticed is that the 1978 driveshaft will not bolt up the pinion flange on the later FF axle. I then figured I'd just swap pinion flanges. NOPE. Can't swap them. Different spline count.

I then noticed that even the universal joints in the driveshaft are all different. Later ones are bigger as are the bolts.

I was then thinking about making a custom driveshaft and getting it balanced (not really wanting to though).

I then decided to pull the rear axles on both and compare the end splines to see if they match. Yes they do - and thank heavens.

So it seems I can take the complete center section out of the 1978 1/2 ton axle and swap it into the 1987 FF axle assembly assuming the 10 bolt holes line up. At least I know they both use the same axle spline count and OD.

I suspect if this Toyota was a 1979 instead of a 1978, all this would be MUCH easier.