Antilock Brake HELP
 

I've got a 93 G 20 Conversion Van and the antilock brake light come on when I give it some throttle. Just as the light comes on, the van seems to loose power as if the antilock brakes are activating. I pulled off the rear drums and found that I'm metal to metal. New parts are on the way. Could this cause the antilock brakes to engage? Also, how do you tell what transmission you have?
Either a 4L60e or 4L80e. How do you determine if you have RWAL or 4WAL. I've been looking for similar posts and have come up empty handed. The Haynes Manual I have would make good fire starter. Absolutely worthless. Thanks for the help.