Buy a 300SD with a bad trans and fix it or pass on it?

[New2MBZ]

I have wanted a 300SD for a while now. I got impatient before when looking for one, and
foolishly bought a nice looking 380SEL that didn't run (was told it was a fuel problem
and it did seem that way), and I learned the hard way that the 380 is not a car with any
demand or even worth fixing really. It still sits in my back yard, partially apart, a victim of
the infamous Mercedes V8 timing chain problem .

II just found "low cost" 300SD, 1981 with 260k or miles. The transmission is bad they say.
I did my research this time before a purchase and the symptom (reverse gear only, lost
forward while going up a hill) seems to be the B2B piston breakage problem.

Now this car is not that close to my location. It has high miles, but I am told it runs
great. I read that if you managed to get a trans with this problem into 3rd gear, it
would drive. While I am not going to risk trying that to get it home.. as I'd hate to
find out it was a broken band, as it exited the transmission case.

I first had a thought that my 380SEL trans would fit the SD, but I have read here that
isn't the case. But I could use the SEL for other parts. I read that the updated servo
piston and parts costs about $100 from the dealer. The car is probably 80-90 miles from
my house. I don't own a tow rig. Say I was to find someone to tow the car for $200 or so,
or maybe even rent a truck and car hauler trailer... what should I be paying for a 1981
SD in this condition? I have played with automatic transmissions a bit.. even rebuilt a
chevy trans years ago, without much to work with. I know the Mercedes transmissions are
a lot more complex, but someone here said their 300SD or the same year I think, had this
problem and they fixed it without even dropping the trans pan. The procedure takes only a
few hours even with dropping the pan, another article says.

The thing is, while it sure sounds like I know what the car needs to drive, and the pics
of the car look pretty good.. I also don't want to have 2 Mercedes sitting around broken,
but I can't afford $3-4k or more for a nice specimen with no problems. Actually, I need
another vehicle to drive soon, as my old Toyota finally gave it up and I let that one go
to someone else's care after over a decade of good service.

Any thoughts on whether this one is worth the chance?