The LATCH manual's entry for the '97-98 Quest is pretty confusing and it also further notes to refer back to the entry for the previous entry for the '93-96 model years. Here's what follows the notes Nannymae quoted from the entry for the '97-98 model years to help us put all the pieces of info. together
:
"2nd Row 2 Passenger Bench Seat: Optional integrated CRs.
3rd row: Is the same as MY (model year) 93-96 information, see above."
The LATCH manual's notes for the '93-96 Quest state:
"2nd Row 2 Passenger Bench Seat or Bucket Seats or 3rd Row 3 Passenger Bench Seat: Use 3rd row TA points. For CRs installed in 2nd row top tether strap must go over 3rd row seat and be attached to TA point. See Owner's Manual for additional information.
2nd Row 2 Passenger Bench Seat: Optional integrated CRs
3rd row: (3) 8 mm weld nuts in U-shaped perforated opening in carpet of cargo area. Remove installed bolt and replace with metric bolt specified in Owner's Manual."
Interpreting all of the above notes from the LATCH manual, the third row can be retrofitted for every third row seating position using the Nissan part number 88894-89900 helpfully cited in the previous post by Nannymae and using a metric bolt specified in the van's owner's manual. Then I believe those retrofitted tether anchors can be used with forward facing carseats installed in the second row if the carseat's top tether strap can reach the anchor, or for carseats installed in the third row. Ideally the OP has access to the '98 Quest's owner's manual to see what it specifically states about using a retrofitted tether anchor for a second row installation and how to route the top tether strap - it's likely the same as noted for the previous Quest model, but confirmation from the owner's manual would be optimal. The unused third row seatbelt as a tether anchor for a second row installation would be what to use until retrofitting tether anchors behind the third row, or if the tether strap for a carseat installed in the second row won't reach the retrofitted tether anchor behind the third row. :twocents: