Its about 5 miles east

The Post Office is at the end corner of the next block (if you are driving Ewa/West bound) The block before Sam's Club, which is across Home Depot. You need to be in the right lane & turn right at the 4 way intersection. The entrance to their lot is on the right, right after you turn the corner. You'll see 24 hour fitness signs on the building across from it.

I visited Hawaii in 1986 but did not make it there.

Yes its 5min but west