Depends on the tractor model. I have several NOS engines, several used and a few rebuildable cores on hand. Most of the time I will either pull what I need off of a parts tractor or just start using a different tractor. My favorite 200 series is the model 214. The 200 (8hp) labored when cutting moderate to heavy grass, the 210 is good but not as impressive as the 214. Never had a 212 or 216 so I can't evaluate them. Run my worker 214 (have 3) with the 2-blade model 38 RM and often cut through brush taller than the tractor without it laboring. Has all the power I need and decent fuel economy. Think it comes down to does the engine have enough power for what you're using it for.How many of you have a back up engine ready to go just in case?