Drilled 180* t-stats on both cars.
1997 SLE (4T60-E,148k miles): After I'm up to highway speed and just cruising - NO getting on it - my trans sits in the mid 160'* while the coolant is 180. I can push hard and it'll get up to 190, maybe touch 200 but I've never really seen it much over. On my trip out west there were several times it hit 195-200 on some of the climbs.
1999 SSEi (4T65E-HD, 102k miles): It takes a LONG time (45 mins) but if I'm only driving highway (75mph) my trans will eventually creep up to 180 to match my coolant. If you remember the video I posted of my 3-4 back to back WOT 0-80 runs (starting with the car warmed up and trans at 180ish), I got my trans up to about 205. It took a good 15 mins to cool back down to 180 while I continued to drive normally.
BOTH cars have pink, unburnt fluid.