I have a 99 Dodge Ram 2500 pick up truck 5.9L. Can someone tell me the gap I need for the spark plugs. Thanks

 

.40 but sometimes its whatever the truck seems to run best with.

Get the Factory Service Manual in the FAQ secton, it has all the cool stuff in it.
Welcome to DF!

 

there should be a sticker on the upper rad support that tells you that info.

 

Pretty sure the .40 above was a simple typo, as it would actually be .040 (.4 is almost half an inch).

I did the tune-up last weekend, and the old ones I pulled out were about .100 (they were gapped incorrectly and badly eroded). Yes, they were gapped at almost an eight of an inch