Cat 511, 521, 541, 552, 522, 532, 521B and 522B Feller Buncher WindowsFront window for Cat feller buncher. 1 1 4" thick, abrasion resistant polycarbonate. Check measurements below against your machine to make sure you are ordering correct window. Replacement for OEM part #s: 321 3794 329 3110 321 3793 Location Dimension Front 23 3 4" x 56 1 8" Skylight option 1 27 5 8" x 20 5 8" Skylight option 2 26" x 16" Door Upper 30 3 4" x 37 1 2" Door Lower 25 1 4" x 15 7 8" Front Sides 'L or R' 58" x 8" If the window you are