A 420SEL's timing chain should probably be changed around 100K.

However, some things you should know about W126 cars:

All V8 cars use a 16-valve aluminum V8 that is super durable if taken care of. They may need valve guides done at 150K to 200K if the car smokes while driving down steep hills; at least that is what happened to our car.

The only W126 V8 to avoid is the pre 1984 380SEL, with the single row timing chain, which can and will break early and often. Most of these cars have been converted to double-row timing chains.

The 380, 420, 500 and 560 are all good cars. A good compromise is the 500SEL....more power than the 380, more torque than the 420, and it runs on regular gasoline, vs premium gasoline as in the 300, 420, and 560. The 380 also will run on regular gasoline.

I would take a 3.8 liter V8 car over a 3.0 liter inline-6. Thanks to the rear-end gearing, the 3.0 liter W126 s-class will turn near 3,000 rpms at 60 mph, while the 3.8 liter car turns around 2,100 rpm at 60. Plus, the M103 inline sixes have more head-related problems than the V8s seem to have. The only head-related problem on the V8 was slight valve guide wear, and then the t-chain broke at 196K (about two months ago) because we were dumb and never changed it. If you find a gas car will all service records, etc, you probably won't go wrong, whatever you do.

Oh yeah, the 560SEL could be found for around 7K, and it would smoke a 300E in a straight line. Fun, huh?

-Sam