How-to: change speed sensor.
" REPLACE SPEED SENSOR IN 1996 FORD CONTOUR
(For Zetec 2.0L) Set parking brake, jack up car on front driver side. Remove Drivers side front wheel. Crawl under car by firewall. Look up on transmission (mid vehicle), you should see the bottom of the VSS as it screws into the top of the transmission - loosen VSS (turn 1/4 turn). Open hood, Disconnect neg cable from battery (safety first) remove 3 long bolts holding down air intake over throttlebody. Unclip air filter top cover. Disconnect MAF connector. Lift off entire top air assembly, disconnect IAT sensor from under intake tube by MAF and put whole assembly away. You need to remove the rest of the Airbox, close to the firewall is a rubber band O ring holding down airbox, unhook. Then Pull up on airbox. You need to pull hard, it is held on by pins that push through rubber donuts on each side of the box. When it comes off it'll make a huge pop and you'll swear you've broken something - you likely haven't. (It's super easy to put back, just push down - hard to remove though). With airbox off, you will see large wire harness, follow it back - as it reaches under the brake booster and throttlebody, you will see a small offshoot with a connector - that is the VSS connector. Even though it's fairly easy to see it's a PITA to unhook. One-handed shennanigans, and some cursing required. Some small hands or really long needle nose pliers would help. Be careful, don't mess up the harness/connector side. When it's disconencted, go back under car and unscrew VSS and pull up. Then install new VSS. Reconnect nrew VSS to harness connector - hard again but not as bad as disconnecting. Then put everthing back together in reverse"
Information is courtesy of R.SLOGAN.