Not speaking from experience but there's no way you're gonna be able to get a new gvr4 sending unit. The OEM units might not be discontinued but would be really expensive. I've found that even for pretty common vehicles the auto parts store sending unit is also quite pricey.
Try disassembling it and sandblasting it. If your tube is about to break off, maybe look into getting an AN bulkhead fitting. Someone locally once mentioned that they knew how to modify the 1g sending unit to work. I don't know how, and I've never looked at them side by side.
And not sure what you were asking, but you can use a fuel pump from a 1g.