Thanks, I read a recent post suggesting that Pioneer's TS-A1675R 3-Way 6.5" speakers fit without modification as well. The poster has a 1999 986 as I recall.

I Did the same MOD without cutting the baffles, just making the inner center of the baffle a little big, you could use sand paper or a box cutter to start cutting around and finishing with sand paper. I used the same speaker! Polk 6.5 db651!!! Nice mod, less than 10 min per side. Using a rotary tool with a sand wheel start enlargign the inner of the baffle till the new speaker seats without problem. I start it with a box cutter all around, cause my rotary tool was dead with no charge! Then with a 5mm sheet foam from Michael's, fill around the speaker to keep it seal!
See pics

Does anyone know the mounting depth using the OEM baffle?

Did you guys rewire the door speakers as rear speakers with her new head units?

This is not entirely true. I believed the post where someone said they do but they do not fit. Do they drill into the baffle? Yes. Do they sit into the baffle flush? NO they do not. I just installed these exact speakers yesterday and they do not sit flush in the baffle and there is a gap. I just installed them yesterday. Back to the factory door speakers I go.