i got a project in mind whit my 1987 xj i wanna swap my front end whit a 1999 xj. my question is do i have to swap the fenders two?

 

You don't have to swap fenders but the top corners of the 97-01 fenders are rounded

 

You should swap fenders too. The bottom on the left of the fender when looking at it is missing on the post 97s. You would have to cut your fender and figure out a way to connect the bumper ends.
The fender flairs are different too.

Unless of course you don't plan on using them then leave your old fenders on. Saw it done here in town recently.
My friend (owns a 99) and I thought it looked strange having the rounded header with the sharp corner fenders.

 

It'll look better if you do. If you're really good with the bondo you could probably build up the fender where the gap is and transition it out...but I'd just rather find someone parting it out and pull the fenders while I was at it.

 

SO, didja do it? What happened if you did?

Mine is going from a '96 to a 99 front end.
EVERYONE says "OH, it just BOLTS ON".. Well not in my case. (not perfectly anyway)
Big gap above radiator, outside top, corner screw 'tabs' don't mount to anything, and had to bend out for the rest of upper side 'rail' to meet.
Corner by headlights needs re-enforcement to not shake them.

And my FAVORITE.. ...wiring needs to be swapped/spliced from stock 8 pin plug to like a 20pin..
I JUST LOVE WIRING.

E