Even if the Dakota y-pipe bolted right up to the manifolds , they hang down farther under the bellhousing than a car. It would need to be modified to bring it up tighter for road clearance. You'd probably be ahead of the game by having one made. Besides, using good aluminized pipe to fab one, it would probably outlast the Walker piece 10 to 1. They're thin gauge, not aluminized (or aluminized very well) and tend to rust out in a couple years.
If there's no shop where you live that can bend, flare and weld a new one up, a couple of aluminized mandrel u-bends, a length of straight aluminized pipe and the flanges, along with a chop saw and MIG or TIG welder would work. Tedious figuring and cutting the bends to get the correct angle but it's really not that bad to do. especially if you have the old one to go by.