Did you put a suspension lift on your TJ? If so how much lift?
I'm guessing what you bought is a
transfer case lowering kit. It mounts between the frame and the
transfer case skid plate.
Here's text from a standard kit's instructions, it should steer you in the right direction:
Support the transfer case skid pan with a foor jack.
1.Remove the three bolts on the passenger side
holding the crossmember to the frame.Install the
spacers between the crossmember and the frame.
Be sure the cupped end is in contact with the
crossmember.
2.Attach the crossmember using the conical washer
and the 1/3 x 3 ” bolt supplied..Tighten bolts.
3.Repeat the above steps for the driver side of the
vehicle.
Note:Some models may experience interfer-
ence between the transfer case and the skid
pan.It will be necessary to trim the pan to
eliminate contact.