im rollin up on 180k ish. impy has about 160

Up to 195K on my '94 LSS (hard driving over here)
And 141K on the '97 SSEI.

Changed the supercharger oil last month on the SSEI, and watching the odometer due to a non-working sending unit. Been fortunate so far.

My 2000 SE has 221,000 and still going strong! Original motor! Replaced the tranny at 123k with a GM remanufactured one. I love my Bonnie!

204000 miles original engine..replaced drive gear in the trans..wish I woulda rebuilt it but still goin strong I'm hoping to have it another 2or3 years....

1993 Bonneville 344,xxx second tranny is on its last leg, won't go into overdrive ( has 2 1/2 quarts of Lucas trans fix in it now)
1998 SSEi 193,xxx Original tranny with shift kit (change the fluid every 40-50,000)
1999 Buick Park Ave 202,xxx Original tranny with shift kit (change the fluid every 40-50,000 )

2003 SSEi just rolled 120K and still going strong. It has handled 350 HP and the heavy right foot for over 50K miles now with no issues.

my bonnie has 190 second trans and third intake
yukon has 170 oem trans amazingly but second rear end
monte is still a baby at less than 70
firebird would depend on what part you are talking about

172k as of yesterday afternoon.

99 Bonneville, 275,000 miles...original engine and trans.

2003 Bonneville SLE 350,000 miles. as far as I know original engine and transmision. i purchased it in 2010 with 207,000 miles