Interesting T-10 4 Speed Can You Help ID?

[marxjunk]

GS tail housing was used in 65 66 GS Buicks..hence GS it put the shifter in a specific spot for the Skylarks..the original nail head t10s had high nickle gears and where very HD for the time..then..they where used as an over the counter HD transmission later...and i have seen them with as late 1978 date codes...

ive seen 2 or three with 72 dates and a few with 74

im sure theres other applications etc..i have never found anything really definitive why a 65-6 GS tail is on a 72 trans, but ive seen them...