Just a heads up, the pan Rockauto advertises for 57/58 371 does not fit. The ad says passenger side dipstick but it is not. The pan is made by Pioneer and appears to be a decent piece if you have an engine it fits. In all fairness to Rockauto the Pioneer site says it fits the 371. Looks to me like late model stuff and Pioneer rep said he thought 350. I have notified Pioneer and Rockauto.
I am now on the hunt for pristine 57 pan.