If you find an unmarked housing, you must either decode the BOM number stamped on the housing or take it apart, to detrermine if it is a Dana 60 or 61. Of course, Any ratios faster than 3.54 are give-aways. Unfortunately, there are 3.54 and 4.10 geared Dana 61s also.

Any housing with a "60" cast into the bottom right side web will be a Dana 60.

I recommend late 60's International, Dodge and Ford 3/4 ton pickups. Make sure the housing you choose is wide enough to be cut to your desired dimension and offset.