My MSD box and coil are both under the dash. Use an MSD Firewall Feed Thru pn 8211. It works great except that the coil is noisy. ...'sounds like Grandpa Munster's basement laboratory.
I put one under the wiper cowl on the 70 Firebird we did and the other I did recently was hid in plain sight one the cameo inside the truck disguised like a heater. As long as they have room to breathe I think they are fine.
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Mike Redpath
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