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Transmission interchange/compatibility


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Well my 720 work truck finally bit the bullet after a year of hard service. I was wondering if I might be able to salvage the 5 speed in it and replace the 4 speed in my 620? I'm pretty sure they'd line up, but I wanted to know if I'd have to modify the driveshaft in anyway or if there'd be fitment issues. Anyone have any info?

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Well, the main issue would be the "tilt" due to the different clocking of the L-series vs NAPS-Z engines. The transmission would bolt up, but the shifter would be offset to the Passenger Side, and the rear mount would no longer be level causing strain on the engine mounts and transmission mount as they "fight" to gain an impossible match.


Lengthwise, they're identical.

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Depends on at least two things.


1/ Do you have a 2 wheel drive '80 720? This is the only year that the 720 used the L20B motor. This year of transmission will bolt up to the 620 L series motor. Why a 2 wheel drive? 4X4s don't have provision for a speedometer drive in the tailstock as it is driven from the transfer case.


If the above is YES:


2/ How long is your 720 transmission? Nissan uses two different lengths of transmission in the 720. They are 26" and 31.5" in length. If yours measures 31.5" it will fit any '73 and on 620 that had the F4W71B 4 speed in it.

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Any non-Turbo 280Z/280ZX transmission fits, and the '77-78 Z car one is virtually identical in gear ratios to the '77-78 truck one. The '82-83 ZX transmission has a very tall overdrive (nice on the freeway with no load) but a very short 1st gear which makes getting going from a stop with a 4-cyl truck fairly slow.


With the exception of the '72-73 and early '74 620s that use the short transmission, that trans swaps in virtually identically. Only issue is the throwout bearing collar and speedometer cog, which in the case of the T/O bearing you just use the one in the truck already. With the speedo cog, some swap and some don't.

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There is a way to swap a few parts and make this work. Perhaps do this yourself if you have a drill press, a tap, 12mm ratchet, snap ring pliers and sealant, or even pay a tranny shop to do the work.


What year 720?

How long is the 720 tranny?


You probably have every thing but the tap so maybe $20 to do this.

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