The one I linked above is the proper one to use for TBI injection with Vortec heads. It's a GM part. I found mine on eBay for a lot cheaper than new, so check around, you might find one. Otherwise, there are a ton of carbureted ones but not a lot with the rear coolant outlet. You'll have to look around. Update - part numbers 12486572 or 12496821. They are the same part, just different numbers for some reason.