Mulisha620 Posted September 10, 2011 Report Share Posted September 10, 2011 I was at a buddy of mines house the other day. I noticed a Datsun 720 KC sitting in the back of the property, and long story short, I was told I could have it if I wanted it. I am working on my 74 620. Are there parts on this truck that I may need at some point in restoring/driving my 620? Maybe parts for disc brakes? (I didn't even look to see if it had discs but I'm pretty sure it does?) I looked at the plate in the driver's door frame and got the vin, is there any way I can identify exactly what year this truck is? Also, it's not 4x4 it's 2 wheel drive- Leaf springs aren't interchangeable are they? Only the 1980 720 4x4 ones are right? Any info would be much appreciated thanks guys... Quote Link to comment
datzenmike Posted September 10, 2011 Report Share Posted September 10, 2011 Truck build date is on the door pillar tag. June to December of any year is actually the next model year... for example 09/79 wouls be an '80 model year truck. Take a look at the motor... if it's an L series just like your '74 then it is an '80 720. 1980 was the last year the L series 4 cyl was used and the first year production of the 720. So if.... '80 720 Motor and transmission will swap although you will need to use your exhaust manifold in order to fit your down pipe. The motor is 3/4" taller so keep the motor mounts in case needed. Check tranny length... if 31.5" it's a perfect swap. If 26" you may be able to use if you also swap the longer front of the two piece driveshaft as well. Tranny is also a wider ratio*with a lower 1st gear that what you have now. Rad is likely the same. Brake master will swap but is larger bore. Booster appears larger diameter and may not clear the clutch master or the steering column just below it. Throttle cable appears the same. The distributor is a highly sought after EI matchbox type so get that and the coil for a high voltage up-grade. (peripherals such as starter/carb/alt/fuel pump/water pump are the same or will swap) The '80 has the same disc brakes as the first year '78 620 but will not swap to your truck. Rear brakes/drums should fit. Differential is higher geared at 3.889 but is matched*to the lower 1st gear in the transmission. Might be a good idea to swap both as a set. Axles and case are wider than the 620. '81and up Begins the use of the next gen Z series motors. They will fit the 620 but you must swap the transmission and motor mounts with it. Carb is on pass side so throttle cable and a few other things must be swapped to make this work. I have a Z24 in my 620 so it fits/works. Rad, carb,alt, starter are different enough to not work well. The Z22 is about 22% larger displacement, the Z24 is about 33% larger. The Z series are not screamers but they have monster torque for pulling a heavy truck. Diff and axles same as above until '83 when the larger Z24 introduced and even higher ratios were used.. Quote Link to comment
Radiant-Designer Posted September 10, 2011 Report Share Posted September 10, 2011 Does it have an l series motor in it? 5 speed trans? What's in your 620? Quote Link to comment
datzenmike Posted September 10, 2011 Report Share Posted September 10, 2011 The '74 should have the L18 and at most a B type 4 speed. Quote Link to comment
Radiant-Designer Posted September 10, 2011 Report Share Posted September 10, 2011 Lol damn Mike meat me to it by seconds, but with lots more info. Quote Link to comment
Mulisha620 Posted September 10, 2011 Author Report Share Posted September 10, 2011 Datzenmike thank you for the info- I am realizing you are a wealth of knowledge, thanks man... My truck is a 74 620 with the stock L18 and a 4 speed manual trans. (how do i figure out what type of trans mine is, I need to look at the transmission id number I'm guessing?) So if the carb on this 720 is on the drivers side of the engine, it's an L series? and therefore a 1980? Because the Z24 carb is on the Passenger side? Which digits of the vin from the 720 door jam plate are the build date? I opened the hood to look at the engine, but you can't see the engine at all... The engine compartment is completely rat-nested... All the way from the cross-member to the hood. You literally can not see the engine.. I will have to pull a bunch of it out to even see if there is an engine in it! LOL Quote Link to comment
Mulisha620 Posted September 10, 2011 Author Report Share Posted September 10, 2011 Ah the build date is in the right upper corner of the door tag right? I remember there being a "/81" there.. Not sure about the first number (Month).. So this truck is a 81/82? Quote Link to comment
datzenmike Posted September 11, 2011 Report Share Posted September 11, 2011 The F4W71B transmission should be 31 1/2" long on your '74. There are no ID numbers for the 620 trans. The 720 lists the tranny/diff and motor size on a tag under the pass side hood hinge on the inner fender. Quote Link to comment
justin 620 Posted September 11, 2011 Report Share Posted September 11, 2011 If it's an 81, it should have the z22, right? Quote Link to comment
datzenmike Posted September 12, 2011 Report Share Posted September 12, 2011 Yes a Z22S motor from July '80 to Oct '83 build dates. Quote Link to comment
the nice machine Posted February 5, 2012 Report Share Posted February 5, 2012 Hey i've been doing my research here on ratsun. i've got a 79 620 kc with an L20b. I've been wanting to upgrade to a 5 speed and put in an air conditioner. the engine is running weak, a few wrench monkey buddies of mine say it really needs to be rebuilt. So i went and bought a 1980 720 with an L20b 5 speed and working air conditioner for 500 bucks. it runs good, it has more power than the one in my 620 (and the 620 has a weber carb, so that aint right), i think i made a good investment. i read on another thread that the '79 620 and '80 720 have the same wide ratio gear set , right? so putting the engine and tranny from the 720 into the 620 should be a relatively easy way to go...let me know if i am wrong. what about the air conditioner? is there a way to put the unit from the 720 in the 620? i haven't got the new one at home yet so i haven't had a chance to dig in and check it out, i'm just excited to get things going this week when i get it home. Quote Link to comment
datzenmike Posted February 5, 2012 Report Share Posted February 5, 2012 You're on your own about the air conditioner, but yes the '79 620 and the '80 2wd 720 had the same motor and transmission. the engine is running weak, a few wrench monkey buddies of mine say it really needs to be rebuilt. So i went and bought a 1980 720 with an L20b 5 speed and working air conditioner for 500 bucks. it runs good, it has more power than the one in my 620 (and the 620 has a weber carb, so that aint right), i think i made a good investment. Makes perfect sense that a good '80 L20B would out power a tired '79 L20B even if it does have a Weber. Put the Weber on the '80 motor for even more go. Quote Link to comment
the nice machine Posted February 5, 2012 Report Share Posted February 5, 2012 cool, thanks. Quote Link to comment
AtomChurch Posted February 5, 2012 Report Share Posted February 5, 2012 Mike is a datsun computer. Quote Link to comment
Jester Posted February 5, 2012 Report Share Posted February 5, 2012 Mike is a datsun computer. Ya think!? Quote Link to comment
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