Identify Engine Year...

I have a '91 XJ Sport. 2-dr, 4.0L, AW-4, 8.25 out back. I bought this a while back for lke 600 bucks, and it's not in bad shape and runs pretty good with some minor fixes needed. Now my main question is, when I went to the dealer to get the breather tube (goes from the valve cover to the air box) they said the one that fit mine was for a '96 engine. Now also, I read somewhere that they put in an interlock thing so you have to brake to move the lever out of park in '96, and mine does that. Are there any date codes on the block that I could check this with? Thanks, if you need anymore info please let me know.

The date code will be engraved into the block high on the passenger side towards the front of the block. Small, thin, engraving. Rub through the goo, then give it a shot of brake cleaner. You'll find it.