Replacing main bearings without removing the crank

Have a 318 that runs great but has a thrust bearing with lots of endplay. I have said **** it and driven
it for almost 50K miles no change? It was a 100 dollar junk yard motor I put in just to get the car running. I plan on a front end rebuild this winter, so I will drop the pan and replace thrust and mains using this method on the cheap?