Efficient tool and time use would dictate having at least 2 gang holders -one immediate use and have another being prepped -
Stamp trans
stamp block,
check...
block stamp legible?
if block stamp is illegible***
return current gang pick up gang for the next vin but changed to current...
The returned defective current reloaded to next vin... (could explain why some are seen with either the next or previous car's vin on the trans as well as differing gang stamps with same engine trans vins)
As a measure The trans should never have an issue with characters being differing heights in the gang stamp... the engine blocks on the rough surface... that is entirely different.
I am going to go out on a limb here and taken an educated (I stayed at Holiday Inn... j/k - but I did take a 90 minute class at the NCRS National event this week on Broach pads and Assembly Stamps) guess why this could be.... the rough area near the oil filter boss is DIFFICULT to stamp into, CAST IRON... and is not very level, repeated heavy blows against such surfaces could cause irregular wear to characters as well as the GANG holders and Spring pins causing another gang holder being required to complete the task.
***We think many of the block stamps are illegible, however they were stamping on the rough surface which was FRESH ORANGE PAINT - a fresh strike in fresh paint will leave a shiny impression which today could appear as nearly invisible.***