The oil pressure sender is just on top of the oil filter housing and points toward the firewall. You can see it easily if you look at the oil filter from above. It doesn't thread directly into the block, it threads into the oil filter housing.
Retired my 94 YJ 4cyl 5spd @ 200K
Now in a 04 TJ 4cyl 5spd CV @120K+
Both as a commuter vehicle in NW, NJ
April 2012.downsized and now a 99er.