1994 Toyota Pickup 2 wd into a 4X4

Yes, but there is only one practical way. Trade in what you have for what you want. If you were to try to transplant all the necessary parts, you would have double what the truck is worth just in parts, and a whole lot more in labor. You'd need the front axle assembly, front drive shaft, transfer case, shorter rear drive shaft, different exhaust pipes, different spindles, two half shafts. The floor pan is different to make room for the transfer case and shift lever.

Beyond the dream of simply making everything work, you also have to consider that stronger springs are needed for the added weight, and the braking balance will be wrong. The brake hydraulic system has a proportioning valve that is carefully tailored to your truck's weight distribution and weight transfer during braking.

It's a nice dream, but you'll never see a professional try to do this to his own truck, and especially to someone else's.