Swapping rear end from 1987 Nissan into 1978 620?

[galvatron1984]

I recently got an 87 Nissan standard cab with hopes of scabbing suspension parts for my 620s, the rear end from the 87 is 40.5 in. Center of leaf to center of leaf. The 78 620 is 38.5 center to center on the leaf. The 87 total length is 3.5 inches wider. Both have 10 bolts on the pumpkin. I was wondering if this swap is possible without welding or cutting things, or if the internal differential parts are interchangeable. Looking grim to me, but thought I'd check. Thanks!!!!!

[G-Duax]

Without welding or cutting things....Yeah, grim is the word.

But the center carrier should work if the '87 is a 4-cylinder, as they should both be H190s.

Just pull the axles out far enough to disengage the diff, and take the drive shaft off, followed by the 10 nuts holding the carrier in the housing.

Remember, if it is a different ratio, you will have to change the speed drive gear in the trans to get the speedo to read correctly.

And you may have to change the input flange. Not sure what year they went to a larger flange.

I have a 2006 H190 in my 620, and had to change the flange.

 

Why are you wanting to do this ? Is the 620 gears shot ?

Edited March 31, 2019 by G-Duax

[galvatron1984]

Yeah, I've had my 620 for ten years and put 130k on top of her 200... And hauled over a half ton in the bed literally hundreds of times. Last one might have been the final straw. Put 1000 pounds of brick in her and she started stuttering REALLY bad and heard what sounded like bad metal on metal clanking. Like, REALLY bad. Her springs are shot and u joints and carrier have over 100k on them, so I'm not ruling that out, and the symptoms reduced greatly when the load was removed. There's an occasional hard CLUNK when the clutch is engaged to fast from a stop but not between gears. Mostly I just had this newer truck sitting in the yard that I hoped I could scab parts from... I didn't realize it wasn't a 720

[galvatron1984]

Is there a good post about the different rear ends that Datsun used? Tearing into the guts of a rear end is one of the only things I've never done. Couldn't be harder than rebuilding a Hitachi carb, right? 🤣

[datzenmike]

 

Simpler than you think on the H-190. Disconnect the driveshaft. Unbolt the backing plates on each side and slide the axles out 4-6". This will stretch the hydraulic brake lines slightly but will work . Drain the differential and remove the1 0 bolts holding the 3rd member in place. Pull the 3rd member forward to remove. You may need help pulling the axles alternately to disengage them from the 3rd member. BEWARE!!! the 3rd member is HEAVY and will suddenly drop out, so be ready for this. The gears remain together and undisturbed as a unit. Assembly is the reverse of removal.

 

If changing the ratio you will need to change the speedometer pinion in the transmission to slow the speedometer.

[DanielC]

In my experience, you need to unbolt the hydraulic brake lines, but you can leave the emergency brake cables in the backing plates, but unclip the brake cables from the frame to get enough slack.

[galvatron1984]

Thank you so much. It's been years since I've done any rear end work and it was always on old Fords with Dad, it would be swapping out the entire rear end and calling it good. Did the differential swap no problem, but the old one wasn't in as bad shape as I thought. DEFINITELY used and abused though. I'm almost thinking a lot of the noise was there u joint that is visibly rusty around the seals. Any recommendation on brands for replacement? Wasn't happy with the quality of the Duralast ones last time, but I did get 100k miles out of em with some heavy use... 

[bottomwatcher]

https://ratsun.net/topic/74810-i-gots-chinesed/

I went through this a few months ago. All good now.

[datzenmike]

I priced U joints for my 710 and they were around $40 each. This is a much safer bet for good quality.

 

Try to find the ones with grease fittings. This will force you to at least have a look at them now and then when greasing them. Most owners, set and forget.

[Stoffregen Motorsports]

Replaced diff and still noisy? How do the axle bearings look?

[Rays74]

The D21 into 620 pumpkin swap is pretty well known swap, I have two trucks daily driven both with near 100k on them after the swap. Both these trucks see lots of freeway, around town and occasional heavy lifting and the taller gearing (both have 3:70) has been a benefit in all aspects. Now if I lived in a more hilly area or were more of a hauling duties then it may not be the best..... ymmv 🙂