Re: 620 Rear End Gearing

From: datsunaholic
Date: 11/20/02
Time: 5:01:53 PM
Remote Name: 208.186.7.117

Comments

That rear diff was used for many years (well into the 80s) with little modification. For a straight bolt-in mod the 1979 620 rear end is a 4.111 ratio vs the 4.375 you have now. Not o LOT of difference but enough to make it seem like the engine isn't screaming so much on the freeway. The gears from a Z22/Z24 equipped 720 pickup (same differential, slight difference in the axle housing) were even closer, at 3.889, which gets the RPMs down quite a bit.

Any shop that does diff work (like a 4X4 shop) can swap the gears alone- you'd have to get a labor quote to know which was cheaper (I think the gear swap would be).