I have a 77 qjet 17057213 and several 78's 17058213. I found out that the bowls differ. This thread below is a good read: http://coloradok5.com/forums/showthread.php?t=13095&highlight=qjet+rebuild The 77 throttle body assembly is bad. I would like to interchange the 77 throttle body assembly (this has the butterfly valves) with one from my 78. Any problems with this? Will this work? They both look the same but I don't really know what to look for.