If your gonna go through the hassle of swapping axles go with Dana 60's. Very strong and will give you a wider stance.
I agree with Yoat Goat on this one. In all honesty the D44 is not any stronger than a toyota front axle. Some people dont seem to mind busting ujoints and axle shafts but if i was going to put the work into a truck to make it full width, I would just go 60 and call it good. With a toyota you are going to have a hard time breaking a 60.
Another cheap option for rear full width axles are T100 rear axles. They are as wide as a full width D44 and plenty stout. The reason I am so against D44s is because I have a buddy who is on his second full width truck running the same axles he did on his last truck (d44 front, t100 rear). He has broken his front axle at least 6 or 8 times (its open) with 35s, while his welded t100 rear has lasted through one truck already (that at one point had 42s, he broke the D44 first run out with the 42s) and is on its second vehicle in 5 years and nothing has ever broken on the rear. Likewise my other buddy has a toyota front with 37s and an ARB and hasnt broken anything in 3 years.
I have just gotten frustrated with him breaking his D44 every other run and I wish he would just upgrade to a 60. Honestly I cant think of anything he has ever broken on the trail besides some component of his dana 44. Especialy if you want to do 40s....skip the 44 and go 60. The cost of repairing the 44 will quickly rise above the initial cost of a D60
PS. your truck is going to look sick with full width axles and 40s