Even though it's in the same Gen there may be mods to be made. The swap is possible. In your case you're going backwards where I would understand. The aluminum would not crack. I will tell you this I have personally installed a 01 block from pan to PI heads. The engine swap is on this website. Everything else is 99 from intake gaskets out.
Note: Afterthought replace the Coolant sensor and tube that are intake valley (if I remember correctly) before installing the intake assembly. I didn't I know someday I will regret not doing it.
- I had the picture of the o1 intake because I still have the complete top end in my basement from the donor engine. 01 F-150
- The picture of the 99 is on my running trucks. 99 Expy EB 5.4L w/ rear Heating & Cooling.
The engine runs fine. Road trips its great I got about 15 mpg once I got from MA. to FL. (over 1200 miles) last summer, and 10 - 13 city about 10 months after install. One of my many projects is tweaking the MPG with help on this site hopefully.
I had a faulty crankshaft sensor (now resolved) but I believe MPG may have been sacrificed. My driving habits, long idles, and a lot of short trips may have contributed as of late.
If it an EB and has rear AC & Heat and yours is not the mods might be lines vacuum, and electrical, and or heating