Purchase advice 300GD

Hello, for 100 years I have felt I wish for a G, I’m sure it will take a long, long time before the right G-Class is in front of me, yet I have my idea which one to be. A 300GD in long with the engine 603, further on is important to me automatic and air conditioning. I think that would be the W463 or? According to the obvious defects like rust on the disc frame, rear lights and side walls, as well as defective diff. Locks I would like to know where to pay attention to n. I’ve already looked at some, but never dared to buy, I think it’s about time, because the market offers less and less. Would be happy about some purchase tips as well as information about frequently occurring problems with this vehicle! Thanks and greetings Martin