wiring n stuff n such

If you have a stock style starter in your 88, you dont have a continuous battery feed to the starter. A later model mini starter (which came from the factory in about 91) does have a continuous feed.

FWIW, the last box I did was a Crane and you didnt use a continuous feed that I recall. On that one, I made a mounting plate and mounted it under the passenger seat, where you could still access the switches. The wiring can run down the rocker panel and under the carpet to the middle of the floorpan.

For your tach, I'd just run the tach signal wire behind the dash and glovebox to where it joins the wires you ran for your box. Run the wire along with those wires to the box itself.

For power, you can use the ignition switch (under the column) or the fusebox. You can also tap in at the cluster but you have to remove the cluster.

For a ground, find a solid sheetmetal ground and put a ring terminal on the wire and attach it under a screw/bolt.

Just MHO on one way of doing this stuff.

Good luck.

If I remember the wiring of the MSD correctly it should have a bigger red lead that has to have a constant +12V, the other red needs to have a switched +12V. If your starter is stock, it's not a constant +12V. Characteristics of electronic components vary so if the manufacturer is calling for 2 different source types, there is a reason for it. As to the mounting questions of the tach, I would hit the fuse box for a +12V source and find a good clean ground, and run the tach wire behind the dash and meet the MSD.