His information was not all that accurate, the 637 never used the ww carb as it would have been completely starved of fuel. The turbo version was actually the DT478 V6 and 366 & 427 engines never replaced the 637 as it was in the 9500 series, the largest application for the 427 was in 1975 when it replaced
the 432 and 478 V6 gas engines
