I'm looking at a 88 M5 with 220k and an unknown service history. Exterior and interior are both good and the engine is clean with no leaks. My mechanic thinks it has been rebuilt but can't say for sure. Seller wants $6k for it. What do you guys think? How long are the trannies good for? How much to replace it if it goes? It has new front struts but the self leveling is cycling up and down. Any ideas on how to fix or should I just remove and replace with Bilsteins? It also needs a new AC compressor- any one have one of these? If I buy it and it goes south real quick could I part it and recoup $6k?