on a 99 for example, are the 2WD 4 cyl springs the same rate as the 2WD 6 cyl springs?

 

yes

 

Are you talking about the front coil springs? If so, they are the same.

 

yep I am talking coils on an XLT. The reason I am asking is that I am adding a monster bumper (TJM) and want to compensate for the addition weight. I am sure it will drop the front down some and was going to just toss a 2" spacer of some sort in there to pick it back up.