Tranny went bang

[odog]

Ok last night I was leaving work, I backed out of my spot, placed my 69 1/2 ton 4x4 in 1st, let out the clutch and BANG, there I sat. I figured maybe a u joint, but they are fine. The tranny is an sm 420 with a rockwell t221 transfer case. I have no movement in any gear, but when I put the truck in 3rd or 4th, and let out the clutch, the gears grind horribly. Reverse, 1st and 2nd do not do this. I have tried shifting the tcase into 2high, 4high, and 4low with all the same results. Everything shifts fine, but I get no vehicle movement in any gear. What do you guys think. Did I break the out put shaft on the tranny? Maybe the t-case has an issue. I will try to tear it apart 1st chance I get, but as of now it sits at work waiting.