Rear Seat Belts

I have a 1992 and the rear shoulder belt is not the saftey type where the belt locks for use on a child seat. Are there any models of SVX that have these type of rear belts? Will they fit in my 92?
Thanks, Got a baby on the way in July and dont want to give up the SVX for silly reasons.

There should be an adapter to make the belt work.
It is a small metal "H" looking thing.

Do you have your manual? The directions are in there.

I used that with my 4 yr old son and it is such a pain in the butt to get it tight enough with the cramped seat area. I really want the conveniance of the locking seat belt.
Thanks for your help though, if all else fails i'll use the old H again