differential ratio for my 1968 520

[dattruck68]

Looking for the differential ratio for my stock 1968 520 pickup. Thanks

[DanielC]

4.88 to 1

[dattruck68]

Thanks DanielC.

 

A little more info requested re transmissions.  Just bought this 1968 520 PU and it has an automatic transmission installed. I posted a question last month and got the response that 520s did not come with an auto transmission option and that someone must have done a replacement retrofit from another Datsun car model. Understanding and accepting that, 3 questions:

1.  How can I identify which model the automatic transmission is? Cast case numbers etc?

2. What is the stock manual transmission model # for my 1968 520?

3. What is the best resource for getting  a stock manual transmission for my 1968 520?

 

Thanks all.

 

 

[datzenmike]

As the 520 and 521 use a short 26" transmission I'll assume that it would be easier to replace it with a 26" long automatic from the 510 of similar years which saves shortening the driveshaft, and I assume this is an L series engine as I have never seen or heard of a J series automatic. I would ask you to measure the length of this automatic  There were at least 3 with two of them Borg Warner 35 and one a JATCO 3N71B. 

 

BW-35 Muncie. Note cooling lines on passenger side, shifter on left or driver's side used only with column shifter. There is a screened vent opening on the side of the removable bell housing at about 8:00 as viewed from the front. I think the body is aluminum but the removable bell housing is cast iron. (or maybe the other way round. Vacuum line from carb  for downshifting.

 

The Letchworth BW-35 is similar but uses a cable (left side) from the carburetor throttle for down shifting, shifter is on left side also. I don't think there are cooling lines to the radiator but relies on cooling fins on the torque converter and the bolt on screen vent opening in the bell housing on the bottom or 6:00 position. Letchworth is a town in the UK where there was a Borg Warner transmission plant. Probably the same as Muncie Indiana..

No picture. Both BW-35s were retired in March '71

 

3N71B (JATCO) used April '71 and on. All aluminum case with removable bell housing. Shifter on right for use with new floor shifter, vacuum line from intake and an electrical downshift solenoid with switch under gas pedal. Cooling lines on driver's side.

 

If the transmission measures 31.5" long it can only be a long 3N71B.

[dattruck68]

Thank you so much! appreciate the expertise and quick response.

[Charlie69]

What engine is in your 520?  Pictures would help.

[dattruck68]

I assume it would be J13 if it is stock. I have not had it out yet so i dont have enough experience to gauge as is.

 

And actually, more interested in just the stock transmission only as I am going to lose the motor and make this truck an EV. I want a standard transmission with the stock differential. I believe the stock transmission would likely have been F4W63?

 

I think this stock transmission will be geared ok however it may be necessary to change the differential as well in whole or gearing to 4:33? Still researching this.

 

Any recommendations on locating  a differential with 4:33 gearing?

 

Thanks

 

Steve

 

BTW, what is the easiest way to upload my photos to an email/post here? (newbie)

 

 

[420n620]

2 minutes ago, dattruck68 said:

 

BTW, what is the easiest way to upload my photos to an email/post here? (newbie)

 

 

 

[datzenmike]

3 hours ago, dattruck68 said:

I assume it would be J13 if it is stock. I have not had it out yet so i dont have enough experience to gauge as is.

 

And actually, more interested in just the stock transmission only as I am going to lose the motor and make this truck an EV. I want a standard transmission with the stock differential. I believe the stock transmission would likely have been F4W63?

 

I think this stock transmission will be geared ok however it may be necessary to change the differential as well in whole or gearing to 4:33? Still researching this.

 

Any recommendations on locating  a differential with 4:33 gearing?

 

 

 

The J13 didn't have an automatic but possibly the later J15 from Central America or Mexico may have had one. Hurry up and take a look at it and use your measuring tape.

 

EV??? like a battery powered truck??? Electric motors make maximum torque at zero RPMs so you don't want a lot of differential gear or even a transmission. Motor connects directly to differential. Maybe a 3.364?