I have a 73 with l28 motor with weber carbs and its a 4 speed iI want to put a 5 sped in it which one should I use Ive heard a 83 non turbo is the gbest

Welcome to the site. Most of the info you are looking for has been covered many many times. Using the search feature will yield lots of info on this and many other things. That said, I'm feeling generous so here's my take on this.....

The 81-83 280ZX 5 speed (non-turbo) is the typical answer, but there's also a 1980 5 speed with a shorter top gear making the transition from 4th to 5th a little smoother IMHO. These all have a closer ratio than the 77-79 5 speeds, with the 1980 version having the closest spread. Many prefer the longer top gear of the 81-83 for the gas mileage, however the difference is minimal. .773/1 vs. .745/1. Gears 1 thru 4 are identical from 1980-1983. Any one will be an improvement over the 4 speed, especially with a 3.70 or 3.90 rear end, but the 81-83 are probably easier to find. The turbo version is actually a Borg Warner T5 tranny, hard to find, and some say not ideally suited to a N/A car, but this is all subject to opinion.

Check this site out for some comparisons:

http://www.geocities.com/z_design_studio/

Edited April 23, 200915 yr by =Enigma=