[magicoolbus]

Looks like you have a Rockwell t-case. Good in the day, but a 205 is the better choice. If your burb is anything like mine, you also have closed knuckle front axle. Also good in the day, but better choices from the 70's. Going big block, I would suggest getting a roller from the late 70's or early 80's and make a swap of the running gear.