Todd - Looks like that is GM# 591783 or 3845048 from Chevy Master Parts Books (extract pics below). Fits 1948-65 1st Design Muncie 3 speeds for the 2nd to 3rd gear shift fork. The original GM# 591783 was replaced by GM# 3845048 on 7-1-1955.

Here are a couple of available now on ebay pieces you might want to snag as either one will work for your transmission.

NOS GM# 591783

NOS GM# 3845048
Attachments

~ Dan
1951 Chevy 3 window 3100
Follow this story in the DITY Gallery
"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)