The Datsun 5 speed manual transmission FS5W71B found in Datsun 280z and 280ZX
The 5 speed Manual Transmission designated as FS5C71B came with different gear ratios and tail housings. There is a “Wide Ratio” that was produced from 1977 – 1980 and “Close Ratio” that was produced from 1981-1983. You can tell the difference between these transmissions by looking at the tail housing.
I took a Transmission and Differential class, so I know a little about them. The gear ratio is determined by the output divided by the input. You actually count the teeth on the gears to do the math. The “Close Ratio” transmission is favored for the close gear ratios. If your racing, the closer the gear ratios are, when you shift your rpm drop is minimal. Looking at both transmissions gear ratios, the Close Ratio gear ratios are literally closer.
Differences between the Wide and Close Ratio FS5W71B 5 speed manual transmissions
There is some great info out there, I got these images from a post POGDEN made on https://www.classiczcars.com. and touched them up. The red, white, and blue (for USA) are the points mentioned in the article. The black text, are my observations from me looking at pics, may not be consistent. Would like feed back on , please.