Is there a recommended spark plug heat range for a 99 LR DII with 109k miles on it if I purchase Platinum +4's?

 

I do not know what the heat range is.
I ordered my E3 spark plugs from JCWhitney.com and they sent me the wrong plugs, I did not know this, installed then and the truck ran like crap when hot, even worse when it idled for 45 min.
I researched and found out that they sent the wrong ones, they did a warranty exchange at no charge with free shipping.
Now the truck is smooth as Pam Anderson's fake...well, you know what I mean.
SO heat range does matter.

 

Plus 4's come only in one heat range for the D2's so no need to worry.