Typically, engine rebuilders or salvage yards put them on engines, more often rebuilt heads. When they reach a certain temperature (indicating overheating), the center melts voiding the warranty.
I only know as I worked in an automotive machine shop.
I purchased a rust bucket 96 D1 for the reported to be good 5-speed R380 and related parts. Engine condition was unknown. The gearbox ended up being bad (really bad) but I think the engine may be good. Turning it over by hand it seems good and the oil / antifreeze look good as well. The heat tabs make me think the engine may be “newer” than the 125k on the odometer.
I’m trying to convince myself to roll the dice and give it a try in my recently purchased D1 with a locked up engine. Oil and coolant look good and it turns over nicely by hand. I will hook up a battery and check the compression. If it checks out I will degrease it, pull the pan and inspect a rod bearing, install some new gaskets and seals, and run with it.