521 with 720 driveline. Anyone done it?

[scottrod2]

Hello Datsun gurus. I am in central Ohio and have a couple questions. I have had a few 720's in my day and I recently wrecked my 1985 720. The guy who hit me had insurance and they paid me out on the truck and I kept the truck. (thinking since it was so clean I could part it out) In my searches for another 720, I found this 521 that is less than a mile from my house. The body on the 71 is really solid. The truck has been sitting for 7 years since this owner has had it, who knows before that. The word is the gas tank had issues and it was parked, but it will run. It has no brakes, doesnt run currently (but may run on ether). My question is: How much 720 stuff directly bolts up to a 521? I have everything I need on my 720 and I am thinking about purchasing the 521 and putting motor, trans, front suspension, rear, everything into the '71. Is this a huge undertaking or does stuff generally match up? I have welders grinders and decent fab skills, but i dont want to invest a huge amount of time building a daily driver. Any and all comments welcome. BTW, the truck is $900. Ill attach some pics. Thanks Scott

 

[metalmonkey47]

http://community.ratsun.net/topic/36077-resto-mod-521-buildup/

[datzenmike]

I don't suppose the 720 frame is still good? If so, much easier to swap the 521 body on and you get to keep the disc brakes and newer 720 running gear.

 

You could fit the Z24 and transmission into the 521 but would have to shorten the front half of the driveshaft. The differential 3rd member will swap if yours is a 2wd. That's about it.

 

I know it's Ohio but the owner has to understand that there's not a lot of Datsun owners out there willing to pay $900 for a non runner, a shell basically, because parts would be so hard to find. Steering suspension and brakes will cost a lot to replace on it.

 

Talk to him and offer him $400-$500 and leave your number. Call back in 2-3 weeks after he's thought about what he could have spent $500 on. He might have softened up. $900 is a bit much unless you could swap the body onto the 720. If this is the case you have a 521 but with newer 720 everything. Electrical, brakes, suspension, steering. $900 for a body you have to replace everything on is no deal.

[wayno]

I agree with datzenmike, if the 720 frame is good, I would drop the 521 cab onto the 720 frame, I have done it several times.

I actually take it another step further, I use the 720 wiring harness and all that is connected to it, I use the 720 column, I prefer the tilt column, but it works with either, the hardest part is wiring the instrument cluster for the first time.

I can help you with the wiring of certain things, such as the 521 wiper motor, so that it will work just like the 720 wiper motor.

Is your 720 a kingcab/regular cab longbox, or a regular cab short box?

[scottrod2]

Hey guys, Thanks for all the input. Hey Wayno, I was under the impression the 720 track width was too wide to do the body swap. Obviously it must not matter too much if your doing it. I fear that is more time than I want to spend on my driver build, but you know better than I how long that would take. My 720 does have some suspension damage to the pass. side so that might not be good. I seriously doubt the framee bent tho. My 720 was a standard cab shortbed. I agree with king rat. the price on the 521 is steep considering what I am getting. My plan was to get it for around $500, but I wanted to do some research first.

[wayno]

Here is my datsun 521KC diesel on a 82 720 diesel frame with stock 79 datsun 620 wheels and caps.

I understand if you don't want to spend the time on that big of a project, there is a lot to do, if you were to stay with the 521 brake master, you would likely have to strip the residual valve out of it, funny that I didn't have to on my work truck, must be broken, and then all the brake line ends would have to be changed to metric, the non tilt steering column would almost bolt in, as it fits into the stock mount bracket without the rubber insulator, but the lower mount plate would have to be stripped off.

I actually don't know if the stock 521 column switches will bolt onto the non tilt 720 column, as all my 520/21s have a tilt wheel, and a 720 wiring harness, so I have never tried it.

This is what my 520 looks like clearance wise in the front, it has been lowered, and the upper A arms have been lengthened about 3/4 of an inch because is so low.

I actually don't know the fitment of the napZ engine as a whole, although it is basicly the same as the L block.

Since I have made the transfer a few times, with a frame ready to drop the 521 cab on, using the existing 521 wiring, and having a 521 radiator modded for the napZ engine(outlets on the correct sides), I could likely do the transfer and have a driveable truck in one weekend, not counting the box transfer, and not trying to keep it super low, but I have done this a few times.

[phenominitis]

Hey wayno what kind of body/bed mount mods are needed for the swap? Im dropping my 72 521 cab on a 81 720 this week.

[wayno]

This is what I made for the 4X4 cab mounts, I used the stock rubber mounts with these, the stock holes didn't line up with the frame holes, so as you can see in the photos, the bolt sticking up went into the cab holes with the stock rubber in between, and a nut and bolt mounted it strait to the frame threw the other hole, these also allowed me some room for movement, so I could get the firewall as close to the engine as I wanted.

 

 

 

I also used a set of short ones for the front mounts under the radiator core support, as they line up perfect, and center the front wheels in the front fender wells.

Where in washington do you live?

If your trying to keep it low, then you will have to come up with another way to do it, what I did was relocate the cab mount holes, I guess I will find out how it holds up down the road.

[phenominitis]

Im in puyallup and I'm trying to keep it low so I'm thinking I might be able to modify the the mounts on the frame.

[wayno]

Im in puyallup and I'm trying to keep it low so I'm thinking I might be able to modify the the mounts on the frame.

 

The mount holes are about an inch off one way or another except for the front mount holes under the radiator, they fit perfect, without any mods.

The kid down the road did what your talking about, he had two sets of each mount, he cut the ends off the existing mounts on the frame, then dropped the cab onto the frame, then put the extra mounts with rubber isolators into the mount holes over the cut/shortened frame mount brackets, positioned the cab where he wanted it, and then tacked everything in place, then removed the cab mount bolts and lifted the cab off again, and then welded the tacked parts permanently, then dropped the cab back on.

[phenominitis]

Im pretty sure I can tackle the body mount situation. What did you do for the steering column?

[wayno]

Im pretty sure I can tackle the body mount situation. What did you do for the steering column?

 

 

I use the 720 columns also, but you have to keep in mind that I also use the 720 wiring harness, and I intagrate it into what 521 electrical parts I have to, such as the 521 wiper motor, I know what wires have to go where on the 521 motor so that it will work like a 720 wiper motor, the headlight plug wires need to be wired differantly also, round and square headlights have the wires in differant positions, and then there is the instrument cluster, thats the hardest part, some things have to be changed, and it will take a lot longer to explain how to do that than I have time right now, but if you use the 720 column with the 720 wiring harness, everything just plugs right in, you don't have to change a thing, and on a side note, if you use the non-tilt 720 column, it bolts right into the existing 521 mount bracket, very clean, the tilt column is a pain in the ass.