So I just recently got my 2000 Ex 7.3 4x4 back from the insurance company after a lengthy accident repair in which the complete rear(suspension and all) and drive shaft were replaced. After getting the truck back I noted a significant vibration at about 20 mph and 65+ so back it went. It was thought to be the DS or rear and I made an appointment at the local DS shop to have it balanced out. The day before dropping it off, the DS u-joint drops out at the t-case

while doing almost 70 and the vibration was crazy.
The insurance co says to bring it back to their shop so they can fix it. They repair DS and the vibration is still there somewhat. So I look under the truck and see the trans housing is all cracked out(pic1)

. The insurance replaces the trans with a new rebuilt

, and gives me it back on two Fridays ago. At first all seemed ok but it was snowing so I didn't really go above 25-30ish let alone hwy speeds till Sunday night when the roads were cleared. Then the initial(less violent and seemed speed related) vibration was still there at about 20mph and 65+ still

.
So insurance says take it to Ford so the dealer can give it a proper work over. I do and Ford says DS is out of balance and needs balancing. So back to the intial DS shop(that it never made it to the first time). They had to add a bunch of weights to it to balance it and it had a bad u-joint again too so they fixed that. Then they put it in and test drive it, said it was running rough. They pulled supposedly pulled the codes and there is a injector balance code for #3 and #7 causing it to vibrate now even at idle and esp prevalent in gear(r was worse than d) as they told me. I said they are crazy it didn't do that when I dropped it off and I was coming to see what they were talking about. I get there at first it seemed a little rougher at the start-up and he put it in d and r slightly pwr-braked it to show me the vibration and blaming it on the inj balance codes. So I wanted to take it for a ride, as soon as I get in the truck and attempt to but it in D to test drive it, I feel the crazy vibration after the last time when the DS fell out of the vehicle. I put it in R back right back into the spot and look under the truck and the trans is cracked again at the same spot(pic2)

...
The shop says that "Nothing Happened" when they test drove it. He is thinking the Torque conv or the flexplate maybe bad and caused it to crack again as the insurance shop that replaced the trans used the original TC and flexplate from my understanding. Is this accurate, what could keep causing it to crack like this? Any help would be great as I am at my whits end with this and just want my damn truck back running like it was.. Please help..