what does it do when towing??
Dont know - don't tow except for a 6x4 trailer and I use my Falcon for that.

I havent driven or run my 6.9 for any serious length of time since february, yesturday i started it for the first time in over 2 weeks. I for the first time ever heard the sewing machine sound of a seized lifter. It did disapear and correct itself after 2 minutes, but i wonder if its a sign of it being left sitting for months at a time.
I have one lifter that a year ago was loud enough to hear from outside the car. Every time I take it for a decent drive and get it good and hot it get's quieter and now I only hear it as a slight noise at certain speeds from the driver's seat.
My Go-No go gauge arrived from the US today so will order a few new hydraulic lifters from Autohausaz and then go for broke with a check of all static clearances, replacement of any dodgy hydraulic limiters and fitting of the two degree cam off-set keys and then hopefully seal it up and forget about the valve train for a few years.
Due to the 280SE being incapacitated for a week due to rear brake repairs, last week I ran trusty rusty daily. It was good fun, despite the 23l/100km. I'm sure it could be better as I know the valve timing is off, and the injectors need replacing.
But if you don't use up that fuel someone else will Ryan. I am tempted by a new set of injectors as they are not all that expensive.
Bill