The differences were very, very minor. '97's had the NASCAR style exhaust that exited just ahead of the rear wheel. Ford found out this caused discoloration of the wheel from the exhaust fumes, so for '98, the exhaust was extended over the axle and exited out he back in the more customary location just in front of the rear bumper. Both '97 and '98 were otherwise identical, as both years had the same grille and front bumper-

The earlier Revel-o-gram kits had this style grille, but as far as I know the only Revell kits with the '99 style grille were the Lightning and Harley Davidson versions. On that '99 style, the bumper was different, the grille 'dipped' down into it a little, and there were different inserts (the Lighting had a mesh setup, while the regular F-150 had the old style 'bar' setup)-

That's what kind of throws me- the bumper on this one looks like the '97/'98 style, and since the second-generation Lighting wasn't introduced until '99, and the Revell kit is a '99, and Sonoma says (and I believe him!) all the parts are from the Lightning kits, I don't see how the '97/'98 grille and bumper got into the mix, unless he modified them.
But at any rate... I'm really liking the buildup, and yeah, I really think Ford should have built a Super Cab Lighting! (Well, the Harley Editon pretty much was a SuperCab or Super Crew version of the Lightning, but still!) Now if only somebody would do a kit of the new SVT Raptor!