You should consider the GoatBoy Drill Guide, but Ian only does limited production runs on that tool. It will guarantee the height and the angle (3deg) of the rear axle holes, as well ensure that they are across from each other. It is always up for debate whether this is the optimum recommendation. Pros: absolutely consistent between cars with the generally approved recommendations as to where to drill the holes. Cons: no adjust-ability. I have one myself (and like it/use it a lot) as it does remove a variable in the build process and allows me to focus on the other aspects of a build. I think you can achieve similar results with the right type of fence and if it is used correctly. The Down4Derby fence takes the guess work out of the Bullet after it is setup, which is also a nice way to go. Its all a preference.
There is another here who is selling a similar drill guide if Ian does not have any for sale, but I have no experience with it.
PLEASE - do not use the DW drill guide while "propping" up on side of the block with a drill bit to get the angle if you are serious about racing. I have been down this road and it works to some degree, but it will be nearly impossible to compete at the level necessary for racing in this league.