I have owned both an Elan and a +2 and the gear levers are not the same but they are probably interchangeable. The differences are obvious if you have access to the Service Parts Lists for both the Elan and +2. If you don't have access to these lists they can be viewed online at
http://www.rdent.com. On the Elan the "anti-sizzle" metalastic bush fits directly onto the actuator stud coming up out of the gearbox. On the +2 this bushing is integral to the gear lever itself. The +2 gear lever might also be set rearwards a bit more than in the Elan but this difference is minor. If you have access to an Elan gear lever make sure it has all of the special washers for attachment to the actuator stud.
The actuating lever that fits into the hemispherical recess in the gear lever cover of the gearbox are also different. At least they have different Lotus parts numbers, 036 prefix for the Elan and 050 prefix for the +2. It is not obvious what the differences are. I know that the +2 version has a cross-drilling for a split pin used to prevent the gear lever from rotating around the attachment stud. I am not sure if the version for the Elan has this cross-drilling.