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81' 720 4x4 Rear Diff


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I have found that early 4x4s used the same driveshaft yoke as all 2wds, so the diff will swap. Sometime in  or around '82/'83 the 4x4 driveshaft/diff yokes became bigger, and NO you can't merely swap the diff yoke to a 4x4 because the internal spline is different also, I tried that. If you look carefully, '80 (L20B motors) 2wd automatics were mostly 4.375 and should fit your 4x4. This gives you a few more options.

 

If you are wrecking yard searching the diff ratio is stamped on the engine plate under the pass side hood hinge on the inner fender. Look for HF43 (43 is 4.375)

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Hmmmmmmmmmm. Just looked under my hood at the codes. Never mind I have removed my Diff and counted the ring and pinion and did the math to come up with the 4.375. I had a friend help me and he is an off-road guy, and we both counted the same thing. The VIN says I should have a 4.375. My tag says FS5W718  HE38! The reason this disturbs me is now I wonder whats in the front Diff?

 

Any guess?

 

Phil

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720idplate_zps5cd0f2a0.jpg

 

KMY720................................ The K makes it a King Cab, M makes it a Z22 ,Y makes it a 4x4

 

 

JN6MDO6YXBW-16965......... The 10th descriptor B makes it an '81 model year.

 

HE38 is an H-190 3.889 diff. 

 

 

 

Never seen a 3.889 in a 4x4. I've seen it listed in a vague manner but thought it was a misprint. The rear end has obviously been changed. The front ratio is unknown but in mud or loose/soft surface it would spin faster than the back and you wouldn't notice much. On pavement you would.

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Checked the front last night (the old mark it and spin it routine) and the drive shaft was just about to complete its 4th revolution when the mark on the on the left flange made its 1st revolution. So a 3.889 it is! So does that make this easier or impossible?

 

Phil

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OK, OldHillBilly has sent me the info from tag from under the hood. Can anyone decipher it?

 

Tag reads as follows: DATSUN type - KHY720, Engine Capacity - 1952cc, Max HP/ RPM - 92/ 5200RPM(sae), Wheel Base - 2815mm, Engine Type - L20B, Chassis Number - KHY720-********, Nissan Motor Co., LTD, Yokohama Japan 44W11.

 

Tag apparently does not say list Transmission or Trans axle directly.

 

Phil

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