727 trans question

The quickest way is to measure the top bolt holes,the center to center distance.The small block 727 is 7 3/4 inches.The big block distance is 6 7/16 distance.Also the inspection cover plate bolt holes are different.The s/b is very close,the B/RB is larger in distance.You can take the serial number from the oil pan rail and ID the tranny at: www.Mymopar.com in the tool reference section to check what it is,mrmopartech at Mymopar.com