Code Reader

[GM Guy]

I am Looking at Purchasing a Code Reader for all of my vehicles.
1998 GMC 3500 w/5.7 Vortec
1998 Dodge Caravan
1995 Chevy 3500HD w/6.5TD
1991 Chevy 1500 w/ 4.3 V-6
1990 Buick Lesabre

Should I Buy A Separate OBD II Reader and a Cheap OBD I Reader for early GM (1982-1993), or should I Buy a Universal Reader with the specific cables for OBD I?

Any help would be appreciated, thanks!

[6point5]

Check out website www.autotap.com for a cheaper alternative than OBDII. I have never used this thing, but it looks very promising for the price.