C60L wheel cylinders

[Grant Bowker]

That is the shape I exect in Chevrolet CMPs. Visually, I would guess it is a smaller bore than the 1-1/4" used on CMPs, likely the 1 " bore typically found on the half tons.
I don't have the technical knowledge to tell if the greater volume of fluid displaced by the larger diameter cylinders is truly needed or not for safe, efective braking.
On one hand, the smaller cylinders should deliver more pressure for the same input by the driver's foot but on the other, if it runs out of volume before generating enough travel of the wheel cylinders for full engagement the extra pressure is useless.

Coming back to the question of wheel cylinders - parts list C60L-03 gives the following part numbers, all Ford format numbers

Front Cylinder assemblies-
92Y2261 (1-3/8" dia.) Note A
91T2261 (1-1/2" dia.) Note B
C118Q2261 (1-38" dia) note B
Note A - On jobs with 5" Joint. Not used after Serial No. 184-281-27 except when 10.50x16 Tires are used.
Note B - On jobs with 6" Joint and 10.50x20 Tires. On and after Serial No. 184-28127.

Rear Cylinder assembly
91T2261 (1-1/2" dia.)

I came up with the same cross reference you did for the 91T2261 cylinder. For the 92Y2261, I got Dorman W4571 and Wagner WC4571 priced $30-44 Cdn at RockAuto