Alternator wires, starter won't disengage where do the wires go?
How many small terminals do you have on your starter relay?
Are you using the six cylinder wiring?
Are you using the original six cylinder starter relay?
Some starter relays have two small terminals. If you get these mixed up, your problem will happen. If the original six cylinder wiring had a two terminal relay, and now you have a one terminal relay, you may have hooked the wrong small wire up. I think it should be red/lightblue to the starter relay, but I am not sure. Do the test Dennis recommended with the test light, and if it stays on, look around for another wire you may have missed that is only hot with the key in start.