Hi Buckaroo,
like all the other trees (with the exception of the wade, where there is a modification at the front bar pad to accomodate the thick fork) the Weatherly "tree" is named after its fork shape. Like an Olin Young tree has a specific fork shape , a Low Association has a specific fork shape, a 3B and a Weatherly, too. While the 3 B and the Weatherly both are A fork saddles the stock ( the thickness font to back of the fork) measures 4 1/2 " at the 3 B , it measures 3 3/4 " at the Weatherly. That's it. How good the tree = the combined arrangement of fork (and horn), cantle and bars fits a particular horse depends on the bars - bar type (Arizona vs North West (or Wade)) and bar measurements. Superior saddle tree company had a good basic info section on bar type and a pdf whith looots of tree=fork styles on the website. Unfortunately the website does not seem to exist at present.
Hope this helps.
Tosch
(not a Buckaroo - just a recreational rider in Switzerland

, who at this time tries to put a handle on a horse in a Weatherly tree saddle

Who of us non-buckaroos does need the thick fork of a Wade?? )