The Stovebolt Site Forums The Shop Area Driveline third member swap questions.

I don't know what your 56 axle looks like but:

1) Not good welding over rubber. It tends to burn, stink and disintegrate. Maybe you need these?? http://www.currieenterprises.com/cestore/productsRE.aspx?id=2493

2) Your pinion angle is relative to your driveshaft. Doesn't matter if your truck is parked on the slopes of Colorado or the flat deserts of California.

3) I would only worry about the gas tank if it is leaking or your welder chooses to use it to clamp his ground to.

4) If you plan on having a permanent weight added to your vehicle, then that is a consideration. Otherwise, just rested with its own weight.

I hope this helps!