I don't know the numbers for T-tops, but the 360 was fairly common. I have two 4 doors at this time. I don't see many T-top coupes though and don't remember them being a common sight back in the past. The T-top volares were sort of around here and there but I never saw many Lebaron/Dip coupes with them. My wife's 76 runner had them and I chased leaks. The 360 is actually not bad on gas in my two 78's as hard as that may seem to believe.