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520 sd22 diesel swap question


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I have the chance to buy a 1981 720 diesel with 175 000 km with a 5 speed.<div>I was thinking that the rear end from my truck probably won't work because of the low gears. Would the rear end from the 720 fit in 520?</div><div><br></div><div><br></div>

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If you have the J13 engine you likely have the 4.875 rear end.


Remove drive shaft at diff. Drain diff oil. Loosen both brake lines. Remove the four 17mm bolts behind each backing plate and yank the axle out about 6". Remove the 12mm nuts from around the rear diff housing and pull diff forward and out. Watch out it's heavy.


Install in reverse order and fill with new GL-5 80-w-90 gear oil.

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  • 1 month later...

Heres a update:


The j13 removed and Diesel wiring installed.


Cab Removed





Engine transmission installed


Motor mounts


My Old Man burnin' metalcool.gif


rolleyes.gifrolleyes.gifThe cab back on with motor and trans inrolleyes.gifrolleyes.gif Then my wife's camera died so........... No more photos till Friday.


The sd22 is a very tight fit there will be no mechanical fan. The drive shaft will have to shortened. We also had to cut the transmisssion tunnel.

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From a technical a difficulty standpoint, I agree. Very cool and not often done.

Thanks This swap has gone pretty smooth. I could not have been done in my driveway the cab had to come off or else it would have been imposible. I had to swap the whole drive train from (engine transmision rear differential ) from the 720. I also had to use the glow plug controler and the injection pump controler from the 720. We had to make new motor mounts and we used the trans mount from the j13 worked we just had to cut a couple of inches off then weld it on. We had to cut quite abut out of the transmission tunnel and the drive shaft needs to be shortend 2.5-3 inches.

Next weekend I am going to finish mounting up the cab repair the transmission tunnel bleed the brakes and swap the rear end. Then bring it home where I can work it on the small things in the driveway. I hope to be driving it by June.

Does any one know where I can find a windshield for a 68 520?

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I plan on running a puller electric fan, however at this time I only have 1.5" between modded water pump & radiator.


Water Pump Mod:


Wataer Pump Mod


My build thread clearance problems:


520 L20 Clearance Issues


I have read your build thread. Thank You!! We have many of the same problems like the e-brake and the radiator. I think I am just going to take a pry bar to the lever and bend it till the transmission. I also think I can use the the fan from my j13 and if I get creative with how I mount the radiator I should have enough clearance...... Hopefully.

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  • 4 weeks later...

ITS ALIVE!!!!:rolleyes: I t run on the fuel it had in in the lines. I have not plumbed the fuel lines in yet. So it is now a SD 22 diesel 520! It still needs to go to exhaust shop, a custom radiator made, drive shaft shortened,fuel lines plumbed, differental swaped, gauges wired up and I need to find a way to get a windshield from WA to Alberta. I hope to have this done in 2 months.:cool:

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