One time a little bit ago I asked what the diffrence between a TPI, HEI etc.. Was. I got the answer. Then I learned that since my car was carberated it was none of these things.
I was looking on ebay today at distributers and all the ones that say HEI distributor look exactly like mine. With the coin built right into the cap. So my question is do they all take the same distributors?

By the way I have a 84Z28 with a carb 350 from 1977ish

One way to tell if the distributor is like the one you seen, HEI has a single input power wire connected to the HEI cap labelled BAT.

There also would be, since you have a Z/28, a wire connected to the terminal labelled TACH. Another way to identify the HEI distributor you presently have would be to copy down the distributor number and find the pedigree or original application of the dist.

The one on my car now has a wire for the tach and a wire for Bat

All (that I know of) cars from GM were equipped with an HEI distributer in 1975. They were all vacuum advance until about 1980 when they became computer controlled. Does your distributer have a vacuum hose connected to it ? You may have either, depending on if they stayed with the '84 electronics or the vacuum advance of '77.