Scanner
 

What scanner do i need to buy for my 93z28.

One that is capable of doing OBD-I scanning.

What brand and who has them

If all you need to do is pull the trouble codes, you can do it without a scanner, by shorting the ALDL pins, and flashing the codes on the SES light. Shoebox has a guide:

http://shbox.com/1/dlc2.jpg

As far as scanning the ECM for sensor readings, operating parameters, etc., you could use a hand held scanner, as Shoebox notes. You can find older Auto Xray OBD-I scanners on ebay or other sites. You can buy any number of new scanners that will read both OBD-II and OBD-I (optional cables often required). Auto Xray and Actron are just two of many sources.

Or, if you have a laptop, you can get free (for up to 20 uses) data logging software from TTS DataMaster:

http://www.ttspowersystems.com/DataMaster.html

You will need a cable:

http://www.akmcables.com/

Thanks Injuneer