throwing codes

I've got a '99 LS 4-door with a 16 valve DOHC engine, and that's all I know. I'm wondering if it's an ls, ls1 or ls2, and what the engine code is ot where I can find it. The service engine soon light is consantly on, has been on since i can remember, got it a couple of months ago. I took it to advance auto and they did a diagnostic, and it showed up as:

P0133
O2 Sensor
Circuit Slow response
(bank 1 sensor 1)

I know what that is, where it is, how to fix it, etc. I like to think i'm pretty knowledgable when it comes to the engine, but this next one threw me and the Advance auto people off:

P0708
Transmission Range sensor
Circuit high input

Anybody here had/have that problem? If so can you help me out? thanks in advance.

so i took it to cottman transmissions and they said it was the neutral safety switch. they want to buy it from the dealership for like 75 USD but i went to advance auto and they have it for 45 USD. and its just 2 bolts and 2 plug-ins so i'll save myself money from the labor. so if anybody else has that problem too now you have the solution. Thanks!