RP,
It's been a while, but I remember installing a kit on a buddy's '05. At one point, we had the whole ass-end of his bike disassembled. And we were following the instructions carefully.
I believe you are correct, that the '05 and later kits have fewer parts, but my point remains valid: If you buy an opened 'kit', you probably don't get all the bits you need.
For example, how many people know that the pannier kits came with stubby turn signals? The 99-04 kits did. IIRC, so do the new kits. I've seen boxes full of the longer ones sitting in a corner at dealerships. The ones off my bike are on a friends' '79 T140.
If anyone cares, I have the parts info to get the pannier hardware for the 99 - 04 bikes from Triumph. Let me warn you; it ain't pretty.