904 no 3rd gear?Why?

How much did you know about the transmission you took to them? It is possible that someone was prepping that trans for full race use before you got it and removed the governor. I had this exact thing happen to me several years ago and it was just that. Trans builder had prepped trans for fully manual valve body in race trans and removed governor, would shift great 1-2 but absolutely no 2-3 shift. It is an easy thing to overlook because no one expects that item to be removed. It is pretty hard to screw up the valve body kit, but there are a number of things someone inexperienced could screw up.