You grab this fine thread bolt, it goes in thread in frame.

This holds up the rear for the marking of the hole.

We slid a jack in from opposite side, and jacked up the front.

You need to install the front long bolt 1st you can see here where the
backing plate goes, Tighten this just until it starts to bend a bit.
Now snug the other bolt into the bottom as shown. You MUST do this
so that your rear hole you drill lines up properly.

AT this point you have a secure front, and one bolt fairly snug in rear. now,
stand back and look at slider, make sure it is aligned so that it is parallel to the
rocker on the Xterra, nice and level same gap from front to rear. Mark the hole.

Unless you have the mother of all drill bits, (Whatever size it is) you have to
remove the slider and drill. (Or just keep it there and drill if you have right bit.)
We had close size but no cigar, so we remove slider, and drill.

Then we used a step drill bit from Harbor Freight (On sale $10) and drill to size.

Above a right angle drill helps a lot.
I am always concerned with rust as I have restored some autos and seen
what drill shavings do inside a frame. So I hose it down with Rust converter
to head off rust. This comes in many brands. I use DuPont.

Cont.... Maybe MC