I hope by now that you have already found one, but if not, I too had this problem with my old 96 Blazer and my current 98. When replacing the tank, this damn thing broke. I had a hell of a time finding one. The dealer tried selling me something that had an eletrical connector on it. I ended up going through LMC Truck, Truck Parts and Truck Accessories for Chevy, GMC, Ford and Dodge Trucks from LMCTruck.com They have it and it was only $20 before shipping.

 

My vent valve broke also when trying to change fuel pump. To my knowledge there were two kinds of valves. One that you can actually replace, or if your like mine it didn't just come out. I went to a local salvage yard and just picked up a whole tank for around 50 dollars.

 

I have a 99 and the vent is not replaceable. The front vent ties to a rear vent coming from the fuel pump. The plastic tank is shaped such that it doesnt need the front vent. I abandoned the front vent by putting a 10-32 screw in the vent - taped the plastic first and put some sealant. Plugged the line going to the rear vent and all seems fine. The only other choice was a new tank.

 

Would that throw a code?

 

Nothing yet but would only consider it for this tank design. There is no way for the front of the tank to get air bound. The vent at the fuel pump is highest point in the tank. You need to plug the front line and the broken vent or you will get a code.