I think it's just the 8.5 shorties. The 10.5 have given me no trouble in subzero weather.

 

I have the 10.5 shorties on mine, have noticed absolutely nothing when it comes to lack of power throughout the rpm range. The dyno test that were being done saw a loss of about 2hp or so up top, so nothing that you would be able to tell in normal driving or WOT for that matter. The only application that you really need the longer plugs for is if you run nitrous I believe. Its been a while since I last looked al this info up so I am not 100% sure why that is but the last I read you needed the longer plugs for it.

 

Hammer or anyone else, you can usually find those 06+ dual firing coils on the LX board or a Ram that is being parted out. You can get the plugs from the same thread sometimes or call Art at Hensons and order them. If anyone needs any part numbers they are as follows

coils - 56029129AB
wires & harness - 05019952AA

 

I got lucky and found someone selling all the parts they had gathered to do it and had decided they didn't want to bother.