Dan G,
The parts lookup does not show a change the PTO lever/bracket on the 1X6/7 models. I have always preferred the 1X8/9 series PTO lever over the 1X6/7 design as they are easier to engage/disengage the PTO. It may be possible that the change was implemented at the tail end of the 1X6/7 series production run before they switched over to the 1X8/9 series but there's no indication of that in the parts lookup. There would typically be two part numbers listed with a serial number range on each if that was the case. IH was generally pretty good about keeping track of changes implemented in their parts catalogs provided you had the latest revision. Who knows what revisions MTD used in their online catalog. Someone with a set of original IH Parts Catalogs might be able to shed more light on this. Alternately a previous owner may have just swapped the lever out, preferring the 1X8/9 series lever over the original one. Based on your newly acquired 147, we now know that they are interchangeable!