I have an old Sun tach from the late '60s. It is a model SST-802, which I think is the one that does not require an external sending unit. I do not have any installation intructions or the harness. The two terminals are marked "Ign. Sw" which seems to be self explanatory, and 'Trigger.' Where should I connect this? One of the coil leads? Thanks in advance, Jerry Phillips Las Vegas 68 AMX 390 57 Chevy 283