Q. Is that 1.875 the long one or the short one
A. The long one.

The 1929 - 1957 Chevrolet Master Parts & Accessories Catalog
Shows two throwout bearings.
Group # 0.799
36-56 part # 909422, 1 7/8" or 1.8750 long
55-57 part # 900018, 1 9/32" or 1.2813 short

Looks like part # 900018 was only used on 261 cubic inch 6 cylinder and V8 engines.

1954 Chevrolet 3105 Deluxe Panel Truck
w/Factory HYDRA-MATIC