Of course you can use a timing light as the marks are there on the crankshaft pulley. You may have to clean them with some scotch-brite. I found it much easier to see the marks at night. Itís hard to find info for timing specs if I remember correctly (something like 8 to 13 DTDC). But at least you can monitor where it is currently, even though you cannot adjust it. I checked mine when I was failing Smog tests.
94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new
88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new