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auto 521 truck?


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hey has anyone ever converted a 520 or 521 (mine has the L 16) to an auto? Still having so much knee pain after knee replacement, really want to drive my little truck, got new tires too. Sure would be great to be able to drive it on a daily basis...now it just sits and I hate that. Any advice...guess we need to find out a few things about bolt patterns, etc first. thanks for any help, Tana

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I don't see why it couldn't happen. Think you might need to transfer some relays or do a bypass park switch. Just have to measure any auto trans and make sure it is the right length to fit your stock drive line. From what some have told me there are some 510 auto trans the same size as the stock 4speed.


I'm sure datzenmike will jump in and fill in any specifics since he appears to be the auto trans expert. :cool:

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You also need radiator with the lower tank for tranny fluid for cooling.

There should be folks that still have the old auto tranny laying around.

I have one but I'm in California


I have everything actually

We just removed my brothers auto tranny to manual


Hydrulic line

Shifter w/ linkage

torque converter

flex plate

vacuum line to intake manifold

Intake manifold with the vacuum inlet


did I miss anything?

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Here is the 3N71B short tail auto that you need, it's from a 72 510 I believe. Any 510 auto will work but I like the Jatco auto from the later 510s.




The 521 and early 620s used the same 4spd but they had a flange out put to mount the drive shaft to. The auto won't have this and accepts a splined shaft. The Front drive shaft can be split at the U joint to get rid of the mate to the flange and have spline U joint put on to replace it.


This is not a 521 drive shaft but good for explanation. The top shaft coming in from the right has a U-joint with a flange mount just to it's right (with bolts) similar to what you would see on the end of the 521 4spd. What you need is the left hand side of the U-joint below it. The shiny end has the splines inside it that fit into the auto tranny


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  • 4 weeks later...

Here's some info that could be helpful.

Auto trans from 1972 Datsun 510 floor shift (Jatco).




Plates that goes at the end of crankshaft and flex plate.








Hydrulic line from auto trans








Lines from Radiator lower tank to trans.








Vacuum line from intake manifold to kickdown solenoid.





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