My vehicle (early '67) has the L30 engine which I am rebuilding. I noted that the bearing suppliers offer standard and high performance bearings for this engine. I want to replace with the same bearings as it was built with, but have not been able to have the original bearings identified. The numbers on the rear of the con rod bearing shell are as follows: A circled capital A, followed by GMM400, with a number 58736 also. Can anyone ID this bearing so that I may replace it with the same type / quality?? Tahnks for any input.