i am fixing to start my ls1 swap in my 88 obs, its 2wd, no tach, im putting a built 700r4 back in it with the rv cable conversion from bowtie and overdrives, the ecm is a standalone harness from speartech, all my question is making my gauges work properly.. do i keep the old ecm and let it slave off the new one or do i need to do some pinouts and delete it completely? and if so wich ones.. there is TONS of info and diargrams out there but most are for somone doing their own harness