As Todd mentioned the S 60 harness was designed for 1985-1987 L-body's

These cars had a 40 pin bulkhead connector so the S60 harness plugged in.

All 1988 SMEC and newer cars went to a 50 pin bulkhead connector.

As Todd was using the S60 harness he needed a 40 pin bulkhead.

His 1988 had a 50 so he swapped it out for a 40 pin bulkhead.

With L body's the bulkhead is part of the dash harness.

I think you mentioned you have a GLH or GLH-T

Either one should be a 40 pin bulkhead.

GLH will need a fuel pump wire.

Thanks
Randy