Quote: 700R4, 4l60, 4l65E, or 4l70E's where meant to handle ~300 lb/ft of torque stock. They need some serious mods to handle a stroked BB in a heavy car. Heck, they tune the 4.8's and 5.3's down with the ECU just to get them to last in the trucks.
Horsepucky. I have countless friends running high 10's with LS powered F-bodies. Ported stock heads, big nasty cam, 4000+ converter, 125 hit of gas and bone stock transmissions with a good tune. My folks have had a tune in their 03 Suburban for the past 60,000 miles that cut torque management in 1/2, firmed shifts up and really dialed the a/f and timing in on the 5.3 in it and have had nary a peep out of the trans. Many of those miles are pulling a 23' Cobalt. 4L60's are a good transmission. Keep them cool and they'll last a good long time. My wife's TBSS (LS2) had over 60,000 miles on it post-tune and no issues with it either and it ran very very well for a 4500lb SUV with 400+hp.
...Ok Ok, you're right. Put in and let her rip. All those trans guys fixin' them with fragged sun shell/clusters and broke input shafts are just crazy. Just pointing some things to look out for. I have a 4l65E in my 4600lb shortbed 5.3 with 0% TM/abuse with 3200 stall and it has held up driving everyday and track time. Is it strong or am I just careful? I can tell you it would not last behind 600lb/ft of torque, sticky tires, and 4000lbs. of car flogging it for very long.
Went back and read your post this morning. What you said makes sense...I took it as you saying they wouldn't hold up to a stock 5.3 in a truck which clearly they will. The TM is there to idiot-proof them. Less , more read.
, more read. 
