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620 3rd member Identification


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This first one is in my non molested 79 620 KC 4 speed
8Y2 and has a line on top in the casting




This second one came from a 78-79 longbed frame that I am converting to a KC frame to replace my rotten one.
It has a different number. 823 and has no line on top. is one for 4 & one for 5 speed? Or no difference at all?
Thanks

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They were all H-190 differentials with 29 spline axles and side gears, so they will swap.

 

All '75-'78 620 standards and automatics were 4.375 ratio.

The '79 was 4.11 ratio but the 4.375 was an option. There's no way to tell from the outside casting numbers and lettering what ratios are inside. You can lift one wheel and spin twice while the other wheel is stopped and count the driveshaft turns to get the gear ratio well enough, but if taking the 3rd member out anyway the ratio is stamped on the outside edge of the ring gear.

 

37/9 ..... 4.11 and used only on the '79 620 that were fitted with the wide ratio 4 speeds to overcome this lower ratio

35/8...... 4.375 not sure, '79 mid ratio 5 speeds and automatics used this gear.

 

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The faint numbers are likely 38310-P0100 indicating an October '73  ('74 model year) and up differential case casting. The early ones probably would have been aluminum just like the earlier 521 and these are steel.

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The 4.11 would theoretically give better mileage.

 

Lift one wheel off the ground, put transmission in neutral, turn raised wheel 2 times, count drive shaft turns. 

 

If you do have the 4.11 it was normal for it to have a wide ratio transmission with a higher 3.592 first gear. If a 4.375 it would have a 3.321 first gear.

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I have it out and have not put the axles back in yet so that should be easy right now w/ one axle.
The insides were purdy. I sandblasted the back plates after removal and blasted the 3rd member before I
took it apart. I used the KC back plates because some dumbass didn't know what the two threaded
holes were for on the drum so they tried to pry them off thus bending the shit out of the back plates.
Mine only had a few extremely minor bent places around the perimeter that took only a few minutes to fix.

Thanks,
I will post my findings later. 

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My computer crashed when I tried to reply, just now found the time
to pull the damn thang and read it. 
I found these numbers on the big gear
E358 HL 831

The numbers start about where it looks like a 2.
Now King Rat, WTF does 79 + 2 mean? and wtf chunk have I got here?

Joe

 

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On 11/4/2021 at 1:19 PM, datzenmike said:

 if taking the 3rd member out anyway the ratio is stamped on the outside edge of the ring gear.

 

37/9 ..... 4.11 and used only on the '79 620 that were fitted with the wide ratio 4 speeds to overcome this lower ratio

35/8...... 4.375 not sure, '79 mid ratio 5 speeds and automatics used this gear.

 

 

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37:9 or 37/9 = 4.1111

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4 minutes ago, Goemon said:

So will this be Kosher with the 79 4 speed?
Or do I need to use the member from the  4 speed?
I have no idea...

 

I don't know what you have. What's on the ring gear?

 

Either 4.111 or 4.375 will work. There's no really bad choice. The 4.11 will give very slightly better mileage if used primarily for commuting. The 4.375 would be better if a work truck carrying loads.

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OK,
Got it clean, used some fine grit paper & a block
to sand the top color off and it has............ E 35:8 HL 831.............. on the ring gear.

What is it ( ? ) and will it work good w/ my 79 4 speed.
Will I get more or less top end ? IDK
I just know the one in the KC has about 500,000 miles on it, she was my daily for decades.
We also did that picking thang back in the 80's with gas pumps. I put 100,000 on her the first year.
Purchased in 87, the pic is 1988
Thanks
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35/8 looks like 4.375 gears...

 

It's fine with a 4spd around town....

But if you are cruising at 70 on the highway your rpms would be high,  around 3600- 4000.....

5spd will make highway driving better and get the rpms around 3000... 

In my 521 I have the L16 with a 5spd so I like the the 4.375 gears....

If you have the L20b the you could get away with 4.11 with a 4spd....

 

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Stock tires, 4th gear and 4.375 @ 70...... 3,853 RPMs

 

There are many different over drive ratios on different available 5 speeds but is assuming a truck mid ratio 5 speed  or 0.864 (13.6% OD)...... 3,329 RPM

 

 

 

Stock tires, 4th gear and 4.111 @ 70..... 3,621 RPMs  (4.11 gear trucks only came with 4 speeds)

 

IF you put a mid ratio 5 speed in (0.864 or 13.6% OD).....  3,128 RPMs

 

 

 

 

 

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You mentioned the gearing on a 79 620 transmission was different.
Or did I dream that???
I could not find the gears when we went to rebuild it.
Nissan had another gear package but no instructions.
That is what I came up with so I had to put all the old gears back in
Or did I dream that also?

 

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4 speeds...

The F4W63L* marked as an option isn't right. The 510 wagons all had this transmission and the same one as used in the L16 powered PL521

 

5 speeds...

The dogleg shift pattern FS5W60L was only used in the '79 210 and not the later 510 (A10 HL510) The FS5W60A H pattern was used on the '80- '82 210s

 

The 26" long dogleg shift pattern FS5W63A was used in the S10 (not S110) 200sx and was an option in the A10 (later HL510) and the '77 and up B-210. It was not an option in the North American 610 but was used in Japan and Australia in the long 31.5" length.

 

The FS5W71B was used in the 620, 720 trucks, 280z, 280zx 810 and Maxima, the S110 200sx, S12 200sx not after '86.5 and in various ratios.

 

The FS5W71C was never used in the 620 truck, but was used in the '84-'86 n/a 300zx, D21 Hardbody, S13 and S14 240sx.

(The F4W71C 4 speed was used in the Vanette and the '88-'92 D21 Hardbody)

 

The FS5R90A was also used in the 'Jan '82 and '83 280zx

 

 

 

 

The 71B 4 speed was first used in the '74 620

 

F4W71B 4 speed (wide ratio) used on all '74-'79 as the standard transmission.

1st..... 3.592

2nd... 2.246

3rd... 1.4156

4th... 1.000

 

FS5W71B optional 5 speed (mid ratio) used on '77-'79 model years.

1st..... 3. 321

2nd... 2. 077

3rd...  1.308

4th... 1.000

5th... 0.864

 

All years '74-'78 were 4.375 differential except the '79 which was 4.11

'79 used a wide ratio 4 speed with the 4.11 differential

'79 optional 5 speeds used a 4.375 differential.

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