whats the diff. between these two leaf kits?????????

[paintman]

Didn't get any answers over on my build thread, its kind of quiet in the pre 47 forum. But anyway I don't understand what the difference is between these two kits. They both look like they are TCI kits but how can one kit fit 37-54 while the other only fits 47-54?????
http://www.premierstreetrod.com/deta..._LEAF_KIT.html

http://www.speedwaymotors.com/TCI-19...Kit,47159.html


Anyone. And remember you must answer in the form of a question, as if you are playing jeopardy. LOL
So what is...........