I remember reading that another member made an extension for the harness on the interceptor and mounted it in cab, thats what I would do, especially with the skid plates under there.
That gives the ability for anytime adjustments. It would not be hard at all to do...
As for the clunking, mine was doing that after an Isuzu tranny maintenance. I did nothing about it, 6 months later(about 2k miles), I had no 3rd to 4th shifting unless I let off the gas, and then it started thunking into first. I would get it fixed ASAP.