dyt 4000

Hello all. The engine on my DYT 4000 917.275640 gave up and I am looking to do a swap with a new engine. The engine is a 18.5 HP, Briggs & Stratton Model 31P777 0348-E1. I called the local Lawn Mower Service store and and they quoted me $1300 for it. Then, they mentioned of a 33S877-0019...