Is O gauge the same? I purchased older O gauge track but I need to get a O gauge curve track connector for the transformer. Any suggestions? O gauge
Hard wire it to the tracks – solder the common to the center rail and the other wire to both outside rails. That should work.
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Welcome aboard!
Lionel track is O gauge (three rail), but it comes in multiple variations. O gauge sometimes refers to track with 31-inch or greater diameter; O27 refers to track made more cheaply with 27-inch or greater diameter, and various proprietary track systems (MTH Realtrax, Fastrack, etc.) also exist. To add to the confusion, O31 or O27 (and O42, O72, and the like) also refer to the diameter of trackage. A good place to buy track is Menards (they have the O gauge style), but their terminal track is designed for constant voltage operation and will not work with a conventional transformer.
O27 track measures about 7/16" high, while O gauge measures 11/16" high. If any of this is making sense, I must not have explained it properly. 
As mentioned before, you don’t need a terminal track and wires can be connected directly to the track. If you have or can find a lockon (here’s an example at Trainz.com: Lionel CTC O Gauge Rusty Track Power Lockon – Trainz, this makes matters a little simpler but for a permanent layout is unrealistic. I have never purchased a lockon; I’ve just gotten lots of them in assorted lots and the like. After a few years with O you will have more lockons than you ever need!
Actually, O27 was IVES clockwork track. IVES introduced Gauge Zero trains to America in 1900 following up Märklin who invented the gauge a few years earlier to European markets. It was only natural for IVES to want to be compatible with the world leader in miniature railways, which was Märklin. IVES stuck with clockwork trains in both 0 and Number 1 gauges until 1915 when they introduced 3-rail electric trains to their lines. IVES also converted their One Gauge trains to Lionel’s Standard Gauge at that time to compete more directly with Lionel, who was rapidly becoming the American favorite (mostly due to Cowen’s unfair advertising comparing Lionel’s best with IVES’ cheapest but soon enough because of WWI).
But it was too late for IVES to catch Lionel and when IVES slipped into receivership in 1929 the Lionel Manufacturing Company took control of most of IVES assets, including their mechanical train line (and electronic sequence reverse mechanism). Which was a good thing because Lionel would NOT have survived the great depression without IVES clockwork motor and less expensive to produce O27 track. A circle of track and the Mickey Mouse handcar selling for one dollar by the thousands saved Lionel.
Initially O27 was “Lionel - IVES” until Lionel dropped IVES altogether in 1932. Then came “Winner Line Trains” because Cowen didn’t want the Lionel name associated with the cheaper trains. But Lionel improved their low price train line and they became “Lionel Junior”, a “train for little brother”. And eventually when Lionel started manufacturing semi scale die cast locomotives requiring broader curvature Lionel Junior became “O27” to reduce confusion about wether or not a new piece of rolling stock could operate on a specific type of track.
Strangely O27 track with a radius larger than 27 inches is still called O27 even if it produces a 54 inch diameter circle because O54 uses Standard Gauge rail invented in 1906 not lower profile IVES rail invented in 1900.
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I agree, it is overly confusing. I left it at “made more cheaply” because I did not want to make it more confusing!
On that topic, I think I remember reading somewhere that Cowen claimed to have had “thrown the Ives dies into the river”. Typical Cowen falderal (yes, that is a real word!)!
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Your older O is probably the same as newer O track, but it would help if you included a picture with your post.