I have swapped in a few cad lock D44s into trucks that did not have a cad lock D44 in it.

What I've found is with the cad locked into the lock position, on dry pavement, with a sharp turn (wheel as hard to one side as possible) you will get some wheel hop from the inner front tire. It sounds and feels bad, but I've not had any long term issues (when it starts bouncing one tends to automatically not turn as sharp). You don't have that issue with the cad unlocked, but you also don't have a front axle drive without the cad locked in.

I have locked the cad lock in by simply removing the lock housing, and sliding the coupler towards the lock position, and replacing the lock housing so the pins hold the coupler to the locked side. I've not ever had an issue doing that, but my son tells me he has read that you are suppose to build a block to hold the coupler into the lock position. Your choice.

The cad lock housing is 4 bolts, using the slid to lock or unlock the coupler is a 5 minute change that can often be done without jacking the truck up. I've only ever lost a few drops of gear lube through the lock or unlock housing process, so that is not an issue. One can unlock the coupler during the summer months if he doesn't intend to go off road or doesn't believe he will need the front axle drive through the summer, then lock it through the winter.