Indy 800 and Sprint 8 are basically the same inside. The Indy 800 cabinet used a lot more wood. It was heavier, and the cabinet tends to fall apart when moved too much. The two Indy 800's in my neighborhood are both in need of lots of cabinet repair. Now that the Sprint 8 is working, I don't have much motivation to work on the Indy 800.
Sprint 8 is based on a modular metal frame, that is common amongst Tank 8, Indy 4 and Sprint 8. The main differences between these cabinets is the fiberglass top, that holds the controls. Sprint 8 adds a high/low shifter, but the gameplay is basically like Indy 800.
I'm too lazy to take all the doors off the Sprint 8, but it looks very much like the Indy 8 inside.
Here is a trouble shooting tip- If you don't have all 4 coin doors hooked up, the game will autostart and not allow you to change tracks. After the game ends, it will automatically start again. You never get to see the attract mode or select tracks when this happens. I guess all the switches are normally closed, instead of normally open.