Strat,

If you look in the Tech Tips under rear ends there is an article that gives the measurements of common replacement rear and also the original truck widths.

The '57 truck had a width of 62" flange to flange. Unless you are going to buy offset rims to compensate for the wider rear end, you will probably have some interference issues.

I specifically bought my posi rear end based on finding a 62" width so I could keep the interference issues to a minimum.

Good luck!

Carl


CCB