You can replace the rings on a type 4 engine with the engine still installed. I just finished one a few weeks ago. However, If you are going to replace the pistons as well, for whatever reason, then you're gonna have to pull the engine b/c there's not enough room to get something in there to drive out the pison pins. You basically have to loosen the fan shroud and start removing everything (sheet metal, distributor, heads, cylinders, carb/intake set up, etc.) that's in the way. the left side is a particular joy with the oil cooler and bracket. some of the screws on the forward/bulkhead sheet metal are a real pain, but that engine is a bigger pain to take in and out. It's not as easy to balance on a jack as the upright (beetle) style engines. If you do want to get into it and have any more questions, I'll offer whatever advice I can. Good luck with it.