Come to think of it, the end of the CV shaft will usually back out of the hub and rattle around in there every time you hit a bump if the snap ring has popped off. ( ask me how I know about that sound... :lol: )
Perform the test that oldestisuzuist suggested.
In addition, grab the end of each CV axle and pull it toward the engine.
If the snap rings have popped off, you will usually be able to pull the CV axle out far enough to create space between the CV shaft and the knuckle it passes through to engage with the rotor and hub assembly.
As for 4x4 light...I'd begin by making sure that the 4x4 Indicator Switch is present, that the wiring is intact, and that the linkage moves as expected.
Beyond that, I'd have to defer to the experts here to help you sort out the deeper issues that may be present.
I'm not sure what could have been disturbed when the engine and clutch were replaced that could render your 4 wheel drive inoperative.
This may provide others with more clues though...did you remove the transmission with the engine, or did you perform the engine swap with the trans left in the truck ?