[MARKDTN]

As far as 4L60E I tow just leaving it on OD and do turn on the tow/haul. I have towed boats, tractors and cars/trucks on a trailer. Had a '95 Suburban that was just over 200K when we sold it and never had the transmission out. The first Tahoe I had ('01) went 299,956 miles on the original transmission and the second ('07)is still going at about 230K on the original trans with my son. Same thing in my '14 Suburban but it has the 6 speed.

I have an '83 K20 that came factory with a 700R4. The original went about 80k and ate the front pump ('83 is known to be weak). Got a GM reman and it was pulled un-necessarily at about 150K for a noise that turned out to be a bad pinion gear. It was rebuilt again and is still going. That truck towed a lot of trailers in its day. I usually towed in direct (at least up hills) when it was carbureted. With the TPI fuel injection I generally just leave it in OD.