Hello Scotty,
Can you recommend a fairly inexpensive OBD1 scanning tool that can read codes on a 93 Chevy G20 Sportsvan conversion ?
Thanks !

See below: You are better off Googling on that particular vehicle how to retrieve the codes for free. They each have a ‘sequence’ to follow to get the codes.
https://carkiller.com/scottykilmer/qa/obdl-scanners/
With OBDI scanners you won’t get the same wealth of information about the vehicle’s engine and other modules that you would with OBDII scanner.
Also, for reference:
https://obdstation.com/difference-obd1-obd2-scanners/
For convenience, you could also try the follower OBDI scanner for GM vehicles: I strongly recommend you contact Innova (the manufacturer of these tools, and a good company) first and see if it works with your vehicle before forking over the money.
https://www.innova.com/collections/all/products/gm-code-reader-1982-1995-3123#keyFeatureContent