I have a 99 PSD and I only plug it in during the winter months. Sometimes after the block heater has been plugged in I can feel the warmth in the plugs and sometimes not. The truck doesn't seem to get warm that quickly after using it sometimes. Is there a way to check it? Where does it go into the block and how much are they? Are they a pain to replace? I tried a search but I kept getting no matches. Thanks for any info.

Shawn