How hard would it be to install the back seat heater vent out of 89 sr5 runner in 87 dlx

 

It just depends how you define hard .

on a technical level quite easy

On the labor side could be a good day to weekend.

The hard part is running the coolant lines to the second heater core.

the ones I have seen are all above the transmission .

I am sure with some looking and thinking something could be fabricated .

There are much easier ways to get heat into this area.

The stock system is just the easiest when building the vehicle on the line.

 

You have to make the holes in the floor beneath the heater core at the center console. Run hoses to the hood, in the area the heater valve is now. You have to put a T in both of the heater lines to connect your feeder and return lines to.

You have to wire power to the heater fan.

Not that hard actually.