If you're interested in a 126, you might consider my daughter's 420SEL which will be available in early March -- many consider the 420 as the best 126 as it has V-8 power (the extra HP and torque are useful for such a big car) without the troublesome 560 air suspension. As indicated in the thread below, I have had a top independent (no DIY) do just about all the preventative work, including timing chain and rails:
low mileage refurbished '88 420SEL
Only reason I'm considering selling it is that I have gotten daughter a 190E Limited Edition, tho we may keep the S for road trips where it excels.
For official info on older M-B use: