Long story short the shifter in my 96 xjr has been damaged and I now have to play with the shifter to make the "P" light up to start the car. My question is, can i take the shifter assembly from an xj6 and slap it on mine with no problems?

 

Sounds more like a problem with the neutral safety switch than the shifter. Have a look at this vid.
In any event, I do believe the shifters are the same, but wait for one of our pro's here to confirm.

 

I see. Well I pulled mine one night really hard because it wouldn't engage and I believe I broke it. It won't even go all the way around to the 1 2 3 gears. So I'm thinking its broke. I probably broke the neutral safety switch too.

 

According to catalog listings found here.....

Genuine Jaguar Parts and Jaguar Accessories for Classic Jaguars from Jaguar Classic Parts UK


.....Jaguar did make a couple changes (VIN specific) to the shifter parts during X300 production. Not sure how significant they would be if you were replacing a complete assembly and I don't see anything speciific to the XJR as far as the mechanicals go.

The XJR (and V12) do, however, have a specific "linear switch"....the black box attached to the right side of the shifter assembly.

Cheers
DD