I don't know about the 190, but the 560 definitely has plastic
guides. I replaced mine at about 112K and they were in need of
replacement. They were very brittle and a deep brown color.
Find out if the 2.3 has plastic guides. The popular sentiment
is to change them at 100K or 10 years. Don't wait. The cheap
plastic can fail and destroy your engine. A used 560 V-8 runs about