I have a 3100 in my 95 Lumina and have pleny of room to get them without rocking the engine. So I think. I did the front 3 and the boots were very tight. When I moved to the back ones, I tuggen and tugged. The wires are fine, I kinda wanted to keep them. I can't seem to get them to budge. I even borrowed my neighbor's "Spark Plug Wire Removal Tool". I get that thing latched on and they still won't budge. Any suggestions? Will I hurt my engine if I drive with 3 rapid fires upfront and 3 old stadard delcos in the back?