Depends on your budget and available space. Eastwood markets a decent full service version. There is another outfit I've seen you tube vids of too. You can also make one using harbor freight 1k# engine stands. You need to extend the height to get the swing, but its easy enough. This is the route I went. There are youtube vids on how to do this.
You also need to consider how you will support the body. I built a cart that will actually support the body once its on the spit. A frame works too. Either way, use pieces of pipe or similar as standoffs so you can get between frame and body. You can also remove the front clip and mount the firewall directly to it. The front clip isn't strong enough to support the body without some sort of extra support.
There are several threads on here with more information and photos.