Hi,

My name is Roger. We live in Southen Ca. near Disneyland. Have owned a '72 Datsun 1200 fro 22 years. Just installed a remanufactuerd A12a. RPM's too high on freeways. Want to put a 5 speed with appropriate rear end. Any suggestions ? Only one experienced Datsun mechanic in all of Orange County, but he doesn't want to touch it. Otherwise car in great shape. Thanks

Hi Roger, the Datsun 1200 differential is 3.9:1. Some B-210s had a 3.7:1 which would help. But with an automatic, it would reduce the get-up-and-go at lower speeds.

The 5-speed is a great option. Get one from a 79-82 Datsun 210 (chassis B310). 1st gear is not so steep, and the overdrive 5th is much more comfortable on the freeway.

These Tech Section articles will give you a start:
What Diff and LSD should I use?
5-speed Overview

Also see Manual to Auto conversion - how to?

Hi Again,

Just sent another e-mail with the same ? Sorry I couldn't find your first reply which we just read leading to another question if you don't mind. You suggested sapping our 3.9.1 differential with a 3.7.1. How is it identified ? Is it on all B210 5 speeds? Do differentials have such numbers on their shell or what ? Roger

Hi Roger, "Datsun B-210" is 1974-1978, but "Datsun 210" is 1979-1982. Why did Nissan North America make this so confusing? I don't know ...

That being said, either a B-210 or 210 5-speed will work. I prefer the newer 5-speed as it has a standard shift pattern. The older one has a first-above-reverse shift.

Anyways, the 3.7 differential only was in certain B-210 or 210 models. Many of them came with 3.9 or 3.889. Here's the breakdown:

1974 B-210: 3.90
1975-1979 4sp and auto: 3.89
1975-1979 5sp 3.70

> Do differentials have such numbers on their shell or what ?

Or what, unfortunately. You can block one wheel, turn the center shaft 10 times and measure how many times the free wheel turns.