I have had BOTH fail....

Got the tranny replaced at around 13K ......
something wrong interally was making downshifts EXTRA rough.....so the warrentee replaced it.
it never really "failed" though.
My new one is abused daily with NO problems(I have 36" tires) I also run Mobile 1 synthetic ATF in it.

On the engine, I just recently got my 3.5 replaced.
the #1 rod berring went at, uh, lets just say it has "MANY" miles, (never know who is watching)....due to lack of lubrication...(read low on oil)
I had just changed the oil one month prior and it was not burning any oil, but aparrently the rear main seal failed catastrofically causing a massive loss of oil.
Warrentee gave me a new short block...
they are not cheap...total cost was over $7500!!!)

As it was being replaced I got to take a good look at the engine ....They are VERY stout little engines, and even have 4 bolts on the main bearing caps similar to other high performance engines. I was amazed at the little wear in the cylinder walls at the milage I had. And the rods are at least as beefy as a Toyota or Chevy 350.

My advice is to run a synthetic of lower viscosity like 0-40 or 5-50 wieght, as lighter oil flows better and #1 cyl. is the last one to get oil from the pump.

Big Meat VX