If you own an older 4.6 SOHC Mustang, especially an early PI version (99-01) you may be very familiar with the issues that plagued the plastic intake manifolds on these engines. The front coolant passage was known to crack, causing an immediate coolant leak, and leaving many Mustang fans stranded on the side of the road. The heater hose fittings were also notorious for backing out.
Fortunately there’s a fix, and if you’re staring down replacing that manifold now, or you’re looking at doing a repair, this video from Late Model Restoration  will prove helpful. While those of us who are accustomed to wrenching on the old pushrod 5.0 may find modular engines somewhat intimidating from the outside, once you start working on these cars engines you may not ever want to go back to wrenching on an old pushrod.
The video outlines all the necessary steps and parts to complete the intake replacement, and Late Model Restoration has everything needed to complete the job. This includes the intake, gaskets, new alternator bracket, and even a new thermostat. The Thermostat and intake gaskets are a good idea when you’re doing this type of install or upgrade. This is especially true if you’ve never serviced these parts before, after all these years chances are those are past due for a replacement.
Replacing the stock intake manifold should take just a few hours, and requires only hand tools and some metric sockets to complete the operation. You’ll probably want to pick up some fresh anti-freeze as well. When the job’s completed, you’ll have saved a few hundred bucks in labor at the local repair shop, and have some peace of mind knowing your intake won’t crack and leave you stranded.