Back in the day I owned a 1971 Boss 351 Mustang, which were only available with the 4 speed transmission. In 1972, the R code 351 engine was still being offered, the difference from the 1971 Boss being flat top pistons and open chamber heads to lower compression to 9 to 1, but still retaining a solid lifer cam. I was always under the impression that this 1972 R code version was also only available with the 4 speed. Earlier today a 1972 Mach 1 went across the block at Mecum Dallas which was claimed to be an R-code 351 with automatic trans. Ant thoughts on this? Please note that I am not referring to the Q code 351 CJ version which was also available in 1972 with both the 4 speed and the C6 automatic.