RYWIRE Distributor Adapter. This distributor adapter is made for a OBD0 1988-91 MPFI chassis to plug into a OBD2 10-position Distributor. The OBD2 10-position plug is on B-series engines from 1996+ and D-Series from 1996 to 1998.
If you have a 99+ D-series Distributor with an 8-pin plug, see the OBD0 to OBD2 8-pin Distributor Adapter.