Packard Forum Index » General

Something that would be interesting to know is if anyone has a breakdown of which OD revisions went into which years & how to identify. Would be nice to make a chart and post. Don't know if anyone has a B-W book that would have that info such as was posted earlier on which years used the various Treadlevac "P" versions.

The only thing I have found so far is R10, R11 and R12 were essentially the same mechanically but BW service book says 10 was for lighter cars. R11 production went till 55 or so but it and R12 production also overlapped and R12 went to around 60. Some sources say R12 was also light duty, others say opposite. With the different lockout switch and 55-6 with no lockout switch at all, was curious if several different versions of R11 51-6 was used or a completely different R12 those years or they used an R11 & just decided switch was not needed in 55-6.