I have a Canadian 261 Chevy truck engine cast in Dec 1956 with an external oil tube under the push rod side cover. I am using an 848 head, with steam holes, cast in August 1957. Can I use the newer style rocker arms with the offset oil distribution ring and a crimped closed oil tube in the middle of the shafts or must I use the older rocker arms with the oil ring in the center and an open oil tube in the middle of the shafts?
