fuel and temp gauge resistor

[GM man]

Since my LS swap, my fuel and temp gauges haven't worked. I've checked everything I know to check and nothing so far. The float and sending unit are new and there's continuity between the gauge and the tank and I'm pretty sure the ohms are the same between my original sending unit and the new one. I've even swapped out my gauge with another one I had and still no luck. I've got an aftermarket fuel gauge hooked up now and it's working fine. I'm down to it maybe being the resistor? I don't know what to check to see if its bad. And since my temp gauge isn't working either (and both worked fine before the swap) I thought maybe the resistor on it may be bad too??. I need some help from you electrical geniuses out there.