diff troubles

[Datsunny]

what kind of differentials can i put im my 1970 521

[datzenmike]

Just the third member or 'bum' without the housing and axles??

 

Any 521, 620 and 720 2wd. (720 4wd to '82-'83) However there are a wide variety of ratios through these years and a 3.364 is too much of a jump for your L16 or J13. You would want something close to the original.

 

What's the problem with it.??

[Datsunny]

well i have a guy who has a 260 and was all the parts and i was wondering if that would work ?

[datzenmike]

If you mean a 260Z car no it won't fit. Yours is a solid H-190 axle housing his is an independent rear suspension (IRS) with an R-180 differential.

[Datsunny]

well there isnt anything wrong with the stock one i just want to change the gearing so i can go on the freeway i had a guy who offered me 260 parts so i just wanted to check with some guys on the fourm, what do you think would be the best option

[Datsunny]

all i want is to roadtrip in my 521

[veryboard]

If you don`t already have one,Put a 5 speed transmission in it.That will help on the highway.Or You could try some 15inch tires on the back.It would be a little harder starting off,but a little faster once you get going(would throw speedo off a bit)

[datzenmike]

all i want is to roadtrip in my 521

 

A '70 521 should have 4.375 rear axle with an L16, so it should be able to go lower but take-offs will be slightly sluggish, even more so with a heavy load.

 

The '79 620 with maual tranny had a 4.111 rear end which would work nicely and is not too abrupt a change.

 

The '80-'83.5 2wd 720 Long Bed manual tranny had 4.111 also.

 

The '80-'83.5 2wd 720 King Cab manual tranny had 3.889

 

Here, read this post on reading the engine tag info to find out what gear ratio is in the 720 truck:

 

http://forum.ratsun.net/showthread.php?t=7521