I was talking to my buddy about my heater core/lines leaking and he suggested using a piece of tubing and jumping the in/out of the heater core so it doesn't enter the cab then just installing a 12v heater i know there is a good amount of room under the drivers side dash and I could install it with air vents so i can still use defrost. anyone tried anything like this?

 

Those little 12 volt heaters are a joke. Can't get enough BTUs out of one to make much of a difference when it gets really cold.

I used one as a rear window defogger on my namesake 89 SHO and it barely did that job.

You're welcome to give it a try but be prepared for disappointment.