Are L-shaped and T-shaped Magsafe 1 interchangeable? [duplicate]

In short no, there's no problem.

Apple changed the "old" T-models with new L-models.

However, they are exactly the same and I've been using a 85Watt MagSafe charger for years now as it charges much faster. Just do it, and nothing will change, except if you go from 45/60 watt to 85 (it will load faster :)). It's just a new look, the connectors are exactly the same.

Should't be a problem. The interface with the computer is the same. There shouldn't be any issues with overheating or anything. I used the power brick that came with my MacBook Air 11 to power a MacBook Pro 15 all day long while I am working and I haven't had any issues except it takes a bit longer to charge.