Go crawl under the truck with everything off, in 2wd.
Try to turn the front axles by hand, or the front driveshaft. If you can spin the driveshaft or axle shafts, then you have vacuum hubs. If you can't turn them (or only turn a small amount, then you have live axles.
Keep in mind it may be somewhat hard to turn by hand, even with hubs.
If you have live axles, be thankful.
If you have vacuum hubs, you can install avm manual hubs. But they kind of suck too. They are more reliable than the vacuum hubs, but break and/or fall off.
Your other options are to modify the hubs to stay locked all the time (like live axles), or to swap the CV joints (axleshafts) and hub/bearing assembly with a 2000 or newer ranger 4x4 with live axles, or 95-01 explorers with live axles, or 01-05 sport trac with live axles.
2006 F150 FX4 Super Crew - Bilstien 5100s leveled 2", 35" KM2s, 4.56 gears, Detroit locker, Eaton E-Locker, Traction Bars, AEM intake, Xcal 2
2010 VW Golf TDI 6MT