(83 jimmy) hard line to the fuel pump is cut and im going to put in a new line to the secondary fuel fiter but i have a fuel line heater and i like to no if i need that or is there a better way to do this ?

You need the secondary fuel filter.

Weather or not you need a fuel heater depends on what ambient temperatures you expect. If it's an electrical fuel heater, it won't work because they don't draw so much power as to be able to heat the fuel, considering the amount of fuel flowing.

If the heater uses coolant as a heat source, it will probably work, but it would only work when the engine is running and warmed up. But when the engine is running, it's not so likely that you need a fuel heater because if the fuel gels, you won't get the engine running to begin with. Still it can be an advantage to have the heater if it's getting so cold that you need to worry about the fuel gelling --- but the more you heat the fuel, the more power you loose and the less lubricating the fuel becomes. It would make sense to install a thermostat so that the fuel doesn't get warmer than like 45F when it gets into the IP. If it gets cold but not too cold, it might be worthwhile to put the fuel heater into the return line to heat the tank ...

However, there seems to be some agreement that fuel is more likely to gel in the fuel filter than somewhere else. And if there is water in the water separator, the water can freeze. Depending on how the water separator is built and on how much water is in there, that can block the fuel flow. So a good setup might involve a fuel heater in the return line and heating the fuel filter elements (and maybe the lift pump) from the outside (or using fuel filters that have a built-in heater using coolant), both using heat from coolant.

So what are you trying to do?