I think the darn thing is in the computer. factory service manual for mine put's it there. I have a 92 ram cummins and it's in the computer. (read expensive) I heard mine clicking the last time I went up north in the COLD COLD Michigan weather (-15). it was coming from the black box behind the battery, and my volt gauge was swinging with it,(charge,no charge from hand held meter) luckily it went away when the temps warmed up. I looked into the computer but decided it was to expensive to replace new and am JY hunting. still no luck finding one though.
as for the external voltage regulator . that's usually a fix for having a bad computer (saw it on the diesel forums as a fix) or an add on to help charge the second battery. could be an battery isloator also.
