A500 or A518?

42RH is a good one everybody overlooks because its A904 based. I have one I will be building up eventually. They have a numerically lower 1st gear than the 46RH. Gets you out of the hole quicker than the 46RH, plus it's a bit smaller and fits the tunnel better. Drag racers are building the 42RH because of the lighter weight, and lower 1st gear. If built right they will hold up to 500HP I am told.