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620 Auto Trans


KELMO

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OK, so a buddy of mine is looking for a 620.  The only problem is that we can only find em with 5spd trans which is cool but, dude is in a wheelchair so a clutch ain't such a good idea.  So we have been talking about just getting the truck and then finding an auto tranny.  My thoughts are that there are some other model trannies we could use based on the info I have been able to find

 

620 auto trans:

31020-X2400, 31020-X2401(UP TO 8/74) 31020-X2402(9/74 TO 07/77) AND 31020-X2461(8/77 AND ON)

all of the above listed trans show to be former part #'s which tells me it is pretty much the same trans for the production run

 

These part #'s show the same for a 610 (unless column shift), 710 and should all be a 3N71B

The late model 510 (A10) and early model 720 show a similar part # but my catalog does not define what trans it is

31020-X2461 (A10 UP TO 06/78) 31020-X2469(A10 07/78 TO 06/79 :  720 06-79 TO 06/80

 

Am I on the right track and can anyone confirm? Also does anyone have a auto trans they wanna sell me.

 

I found a little info using the search button but not quite what I was looking for.

 

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Pretty much any 31.5" long (ish) 3N71B with an L bell on it will work including the 280z and zx/(Maxima to '82).  You could also use the one from a 720 Z24 and swap a removable L bell onto it, they are (unlike the 4/5 speeds) removable... this wouuld give you a locking torque converter. 

 

I have 710s and they are the correct length as long as L20B, S10s and A10s to '80 with L20Bs should work but ask the A10 guys for the length, 610s I think so, 810s should.

 

Length is the deciding factor, and if it has 6 bolt flex plate. You will also meed the small adapter plate for the end of the crankshaft.. I think you just reverse the 4 speed trans cross member mount to fit the auto. Mix and match.... if you get a Z20E 200sx auto simply swap an L bell onto it.

 

I have three maybe four 3N71Bs laying about, two from 620s. Too bad you don't live closer.

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If you were closer I have a 3N71b with flex plate spacers and torque converter, from a maxima, but the only difference is the number of teeth on the flex plate

 

 

Yeah the flex plates were different. We tried to use it for my L20 swap a few months ago. Its noticeably different...

.

 

Ha ha yes the plates are different but the starter teeth are the same. The Maxima/zx and 720 of similar years use the same flex plate. The differences between these and the older 620 is the locking torque converter. It's larger and the flex plate is shaped differently to hold it. Teeth and starter gears are the same still.

 

enginedriveplates78620and88D-21Larg.jpg

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Thanks for the info guys.  Seems it would be easier to either just find a truck that is already auto......or maybe we should just up and move a little north and then just a bit west :thumbup:

 

Did I mention we are looking for a King Cab also, wanna make this as hard as possible.  Going to keep an eye on PNP to see what pops up, there was a late 510 (A10) last year and I have seen a few 620's and 720's so we should be able to find something sooner or later.

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OK, we went and looked at the 620 and looks like he is gonna get it. Turns out his brother has an automatic 280Z trans, so from what I gathered from some of the above posts.......ha ha I was gonna say compare the flex plates.....der....its a standard.  parts catalog time.

Flex plate and spacer are the same part # for both

12331-E3000 flex plate and 12330-E3000 for the spacer (they call a pilot) between the crank and flex plate. looks like we could be in business.  Need to figure out the shifter assembly and maybe a radiator for the cooling lines (?), no need to worry about the pedal box as he won't be using them.  Sure there will be other things pop up along the way but standing here, not laying underneath the car swearing like a sailor, it seems like it should go well.........

 

Before someone else says it .............Famous Last Words

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