If I remember correctly. Top Fuel, Pro Comp and Competition Eliminator were on the eastside and Funny Car, Pro Stock, Modified, Super Stock and Stock were on the westside. I'm not sure where the motorcycle classes were located.
I think Funny Car got moved to the eastside in possibly 1980?
I've always enjoyed seeing the Pro cars being towed back up return road. I guess if the pit sides were flipped, that would be lost.