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Where exactly is 71B written on the tranny?


ahoogakev

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hi Gang, OK I am trying to find a 5 speed to swap into my 76 620 which has a 4 speed, I understand that the FS5W71B is the 5 speed, and the one I want.I read online that this tranny has 71B cast into it somewhere , can anyone tell me just where it is stamped? I found one in the local scrap yard, but could not see any lettering on it,I did not know where to look,thanks Kevin.Also is the 71C fully interchangable for a 620? That would sure make locating one easier, the scrapyard here is getting real low on 620/720 trucks.

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I'm waiting with bated breath for answers to this question, cause it is one of those things I don't know. I went out and looked at a 5-speed I pulled out of an L20b 720. There is a long number stamped into the top, front of the bell housing, but no 71B in the number. The tranny is kind of buried under other parts, so I can't easily look for other numbers, but I recall looking before and not finding more numbers. There is a lot of discussion here on Ratsun on how to ID a trans by length and appearance. It makes me wonder if there is a magic ID number on the trans. datzenmike, where are you?

 

Len

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The FS5W71B 5 speed was used on no less than four different series 4 cylinder engines and two different 6 cylinders. It also came in two lengths. So, some of them may have 71B on them but won't fit your truck. Identifying an FS5W71B just by that isn't very accurate.

 

This one is just to the rear of the reverse switch.

transFS5W71BID002Large.jpg

 

 

This one is on the other side of the main case.

transFS5W71BID001Large-1.jpg

 

The majority don't have any casting letters. So you need to know what to look for. It helps if the 5 speed is in a vehicle, you can look at the motor and see what it will bolt to. If it's off the vehicle this is more difficult.

 

Your 4 speed will have a small narrow cover plate with 6 bolts and a breather cap on it just forward of the shifter, and look like this:

 

CopyofF4W71Bfrom75620001LargeLarge.jpg

 

The five speed does not have this cover plate and looks like this:

 

trans83Maxima5spd.jpg

 

.

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Ha, just what I suspected - it's COMPLICATED! While I don't like that fact, I like it better than finding out there is a Simple Answer to tranny ID everyone knows but me. So is the number on top of the bell housing a serial number?

 

Jason's ratio chart http://newprotest.org/projects/510/gearRatios.pl shows three different gear sets for trucks. Is one of these sets more commonly found in 620/L20b720 trucks?

 

Len

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The number on top of the bell housing can only indicate the month of manufacture. This is fine if it the original transmission and you have it into the dealer for repairs. They already know what year your vehicle is and only need the month in order to order correct parts in case of any changes in that year.

 

There's no way to know if the tranny was swapped and if it's out of the vehicle you are truly out of luck.

 

There were two different 620/720 2wd 5 spd gear sets available. One in the '77 and '78 and another in the '79 (620) and '80 (720)

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Thank you very much Datsun Mike; that has helped me a lot. I just saw that there are two 1981 or 82 280 ZX cars in my local scrap yard, I want to go down and look at them, I was hoping one would be a five speed. However something you said about them all being different or different ratios, looks troubling ( I better re-read your post) I saw a 5 speed in an 86 DAtsun 720 in that scrap yard yesterday, maybe I will go look at it again and try to find numbers on it too,now that I know where to look. However if I understand you correctly that year truck would never fit a 620, only up to about 1983? Too complicated for me,if I didn't want a 5 speed I'd never do it , ah ha! Thanks again,Kev.

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'77-'78 620, '79-'84 Maxima and '77-'79 280z have the same gear ratio as the 4 speed in these vehicles. (mid ratio)

'79 620 and '80 2wd 720 have the same ratios but different from above. (wide ratio)

'80-'83 280zx non-turbo (close ratio)

 

All the above are transmissions fitted to L series motors and will fit you engine.

Note: There were no 4 spds used on the 280z or zx after '78

Note: only the 2wd 1980 720 had an L series motor and subsequent year 720 transmissions won't correctly bolt to the L series motors. Also check the length as the 720 did use two different lengths. You want the long one that is 31.5" not the 26".

Note: avoid any 280zx TURBO 5 speed. It won't fit your truck. Look for non-turbo cars.

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